sPiDer As preDator

Spiders are predatory invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. They are classified in the order Araneae, one of several orders within the larger class of arachnids, a group that also contains scorpions, whip scorpions, mites, ticks, and opiliones (harvestmen). The study of spiders is called arachnology.

All spiders produce silk, a thin, strong protein strand extruded by the spider from spinnerets most commonly found on the end of the abdomen. Many species use it to trap insects in webs, although there are also many species that hunt freely. Silk can be used to aid in climbing, form smooth walls for burrows, build egg sacs, wrap prey, and temporarily hold sperm, among other applications.

All spiders except those in the families Uloboridae and Holarchaeidae, and in the suborder Mesothelae (together about 350 species) can inject venom to protect themselves or to kill prey. Only about 200 species, however, have bites that can pose health problems to humans.^[1] Many larger species’ bites may be quite painful, but will not produce lasting health concerns.

Spiders are found all over the world, from the tropics to the Arctic, living underwater in silken domes they supply with air, and on the tops of mountains. In 1973, Skylab 3 took two spiders into space to test their web-spinning capabilities in zero gravity.^[2]

Contents [hide] 1 Morphology 1.1 Prosoma 1.2 Sense organs 1.3 Respiration and circulation 1.4 Digestion 1.5 Spinnerets 1.6 Size 1.7 Coloration 1.8 Life cycle 1.9 Lifespan 1.10 Reproduction 1.11 Sacrificial males 2 Ecology 3 Behavior 3.1 Predatory techniques 3.1.1 Spider webs 3.1.2 Hunting spiders 3.1.3 Ambush predators 3.2 Defense 3.3 Social spiders 3.4 Flying spiders 4 Web types 4.1 Tangleweb spiders 4.2 Orb web spiders 4.3 Other types of webs 5 Evolution 6 Taxonomy 6.1 Mesothelae 6.2 Mygalomorphae 6.3 Araneomorphae 6.4 Creatures often mistaken for spiders 7 Spiders and people 7.1 Spider bites 7.2 Benefits to humans 7.3 Spiders as food 7.4 Arachnophobia 7.5 Spiders in symbolism and culture 8 See also 9 Footnotes 10 References 11 External links 11.1 General 11.2 Regional 11.3 Morphology 11.4 Taxonomy 11.5 Pictures 11.6 Other

Morphology

Spiders, unlike insects, have only two body segments (tagmata) instead of three: a fused head and thorax (called a cephalothorax or prosoma) and an abdomen (called the opisthosoma). The exception to this rule are the assassin spiders, whose cephalothorax seems to be almost divided into two independent units. Except for a few species of very primitive spiders (family Liphistiidae), the abdomen is not externally segmented. The abdomen and cephalothorax are connected with a thin waist called the pedicle or the pregenital somite, a trait that allows the spider to move the abdomen in all directions. This waist is actually the last segment (somite) of the cephalothorax and is lost in most other members of the Arachnida (in scorpions it is only detectable in the embryos).

Prosoma

All spiders have eight legs, although a few ant-mimicking species use their front legs to imitate antennae, which spiders lack. Their eyes are single lenses rather than compound eyes, ranging from simple light/dark-receptors to eyes rivaling those of a pigeon (some jumping spiders).

They have pedipalps (or just palps), at the base of which are coxae or maxillae next to their mouth that aid in ingesting food; the ends of the palp are modified in adult males into elaborate and often species-specific structures used for mating. Since they have no antennae, they use specialised and sensitive hairs on their legs to pick up scent, sounds, vibrations and air currents.

Sense organs

Spiders usually have eight eyes in various arrangements, a fact that is used to aid in taxonomically classifying different species. Most species of the Haplogynae have six eyes, although some have eight (Plectreuridae), four (eg., Tetrablemma) or even two (most Caponiidae) eyes. Sometimes one pair of eyes is better developed than the rest, or even, in some cave species, there are no eyes at all. Several families of hunting spiders, such as jumping spiders and wolf spiders, have fair to excellent vision. The main pair of eyes in jumping spiders even see in color.

Net-casting spiders have enormous, compound lenses that give a wide field of view and gather available light very efficiently.

However, most spiders that lurk on flowers, webs, and other fixed locations waiting for prey tend to have very poor eyesight; instead they possess an extreme sensitivity to vibrations, which aids in prey capture. Vibration sensitive spiders can sense vibrations from such various mediums as the water surface, the soil or their silk threads. Also changes in the air pressure can be detected in the search for prey.

Respiration and circulation

Spiders have an open circulatory system; i.e., they do not have true blood, or veins to convey it. Rather, their bodies are filled with haemolymph, which is pumped through arteries by a heart into spaces called sinuses surrounding their internal organs.

Spiders have developed several different respiratory anatomies, based either on book lungs, a tracheal system, or both. Mygalomorph and Mesothelae spiders have two pairs of book lungs filled with haemolymph, where openings on the ventral surface of the abdomen allow air to enter and diffuse oxygen. This is also the case for some basal araneomorph spiders like the family Hypochilidae, but the remaining members of this group have just the anterior pair of book lungs intact while the posterior pair of breathing organs are partly or fully modified into tracheae, through which oxygen is diffused into the haemolymph or directly to the tissue and organs. This system has most likely evolved in small ancestors to help resist desiccation. The trachea were originally connected to the surroundings through a pair of spiracles, but in the majority of spiders this pair of spiracles has fused into a single one in the middle, and migrated posterior close to the spinnerets.

Among smaller araneomorph spiders we can find species who have evolved also the anterior pair of book lungs into trachea, or the remaining book lungs are simply reduced or missing, and in a very few the book lungs have developed deep channels, apparently signs of evolution into tracheae. Some very small spiders in moist and sheltered habitats have no breathing organs at all, and instead breathe directly through their body surface. In the tracheal system, oxygen interchange is much more efficient, enabling cursorial hunting (hunting involving extended pursuit) and other advanced characteristics as having a smaller heart and the ability to live in drier habitats.

Digestion

Spiders can only eat their food in liquid form. For this purpose predigestion is carried out both internally and externally to liquefy the tissues of their prey. Some spiders do this by spitting up digestive juices onto prey while chewing it with their chelicerae. The resulting liquefied “soup” is then sucked up by the spider. Dense combs of hairs around the mouth filter out solids while the spider ingests the liquids. Undigested or uneaten parts of the prey are later discarded. Some spiders do not chew their food, but inject digestive fluids from their stomachs directly into the body of the prey to liquefy the inner tissues and organs. The spider then sucks out the liquefied tissues, eventually leaving the empty outer exoskeleton of the prey.

Many spiders will store prey temporarily. Web-building spiders that have made a shroud of silk to quiet their envenomed prey’s death struggles will often leave them in these shrouds and then consume them later.

Spiders are capable of digesting their own silk, so some spiders may eat their used webs. When a spider drops down on a single strand of silk and then returns, it will generally rapidly consume the strand of silk on its way back up.^{[citation needed]}

Spinnerets

The abdomen has no appendages except from one to four (usually three) modified pairs of movable telescoping organs called spinnerets, which produce silk. The suborder Mesothelae is unique in having only two types of silk glands — thought to be the ancestral condition. All other spiders have the spinnerets further towards the posterior end of the body where they form a small cluster, and the anterior central spinnerets on the tenth segment are lost or reduced (suborder Mygalomorphae), or modified into a specialised and flattened plate called the cribellum (parts of suborder Araneomorphae), which produces a thread made up of hundreds to thousands of very fine dry silk fibers resulting in a woolly structure that traps prey. The cribellate spiders were the first spiders to build specialized prey catching webs. Later some groups evolved (called ecribellate) that use silk threads dotted with sticky droplets to capture prey ranging from small arthropods to sometimes even small bats and birds.

Size

Spiders occur in a large range of sizes. The smallest, dwarf spiders of the subfamily Erigoninae, are less than 1 mm (about .05 inches) in body length. The largest and heaviest spiders occur among tarantulas, which can have body lengths up to 90 mm (about 3.5 inches) and leg spans up to 250 mm (about 10 inches).^[3]

Coloration

Only three classes of pigment (ommochromes, bilins and guanine) have been identified in spiders, although other pigments have been detected but not yet characterized. Melanins, carotenoids and pterins, very common in other animals, are apparently absent. In some species the exocuticle of the legs and prosoma is modified by a tanning process, resulting in brown coloration.^[4] Bilins are found for example in Micrommata virescens, resulting in its green color. Guanine is responsible for the white markings of the European garden spider Araneus diadematus. It is in many species accumulated in specialized cells called guanocytes. In genera such as Tetragnatha, Leucauge, Argyrodes or Theridiosoma, guanine creates their silvery appearance. While guanine is originally an end-product of protein metabolism, its excretion can be blocked in spiders, leading to an increase in its storage.^[4]

Structural colors occur in some species, which are the result of the diffraction, scattering or interference of light, for example by modified setae or scales. The white prosoma of Argiope results from hairs reflecting the light, Lycosa and Josa both have areas of modified cuticle that act as light reflectors.^[4]

Life cycle

The spider life cycle progresses through three stages: the embryonic, the larval, and the nympho-imaginal.

The time between when an egg is fertilized and when the spider begins to take the shape of an adult spider is referred to as the embryonic stage. As the spider enters the larval stage, it begins to look more and more like a full grown spider. It enters the larval stage as a prelarva and, through subsequent moults, reaches its larval form, a spider-shaped animal feeding off its yolk supply. After a few more moults (also called instars) body structures become differentiated. Soon, all organ systems are complete and the animal begins to hunt on its own; it has reached the nympho-imaginal stage.^[5]

This stage is differentiated into two sub-stages: the nymph, or juvenile stage and the imago, or adult stage. A spider does not become sexually mature until it makes the transition from nymph to imago.^[5] Once a spider has reached the imago stage, it will remain there until its death. After sexual maturity is reached, the general rule is that they stop moulting,^{[citation needed]} but the females of some non-araneomorph species will continue to moult the rest of their lives.

Lifespan

Many spiders may only live for about a year, but a number will live two years or more, overwintering in sheltered areas. The annual influx of ‘outdoor’ spiders into houses in the fall is due to this search for a warm place to spend the winter. It is common for female tarantulas to live up to twenty years.^{[citation needed]}

Reproduction

Spiders reproduce by means of eggs, which are packed into silk bundles called egg sacs. Spiders often use elaborate mating rituals (especially the visually advanced jumping spiders) to allow conspecifics to identify each other and to allow the male to approach and inseminate the female without triggering a predatory response. If the approach signals are exchanged correctly, the male spider must (in most cases) make a timely departure after mating to escape before the female’s normal predatory instincts return.

Sperm transmission from male to female occurs indirectly. When a male is ready to mate, he spins a web pad upon which he discharges his seminal fluid. He then dips his pedipalps (also known as palpi), the small, leg-like appendages on the front of his cephalothorax, into the seminal fluid, picking it up by capillary attraction. Mature male spiders have swollen bulbs on the end of their palps for this purpose, and this is a useful way to identify the sex of a spider in the field. With his palps thus charged he goes off in search of a female. Copulation occurs when the male inserts one or both palps into the female’s genital opening, known as the epigyne. He transfers his seminal fluid into the female by expanding the sinuses in his palp. Once the sperm is inside her, she stores it in a chamber and only uses it during the egg-laying process, when the eggs come into contact with the male sperm for the first time and are fertilized; this may be why the vivipary has never evolved in spiders.^{[citation needed]}

Very unusual behaviour is seen in spiders of the genus Tidarren: the male amputates one of his palps before maturation and enters his adult life with one palp only. The palpi constitute 20% of the body mass of males of this species, and since this weight greatly impedes its movement, by detaching one of the two he gains increased mobility. In the Yemeni species Tidarren argo, the remaining palp is then torn off by the female. The separated palp remains attached to the female’s epigynum for about four hours and apparently continues to function independently. In the meantime the female feeds on the palpless male.^[6]

Sacrificial males

Main article: Spider cannibalism

It is a common belief that male spiders, which usually are significantly smaller than the females, are likely to be killed after or during mating, or sometimes even before mating can occur.

Even in some species of widow spiders, which are named exactly for this belief, the male may live in the female’s web for some time without being harmed. However, in over 60% of cases the female of one species, the Australian redback spider, kills and eats the male after it inserts its second palpus into the female genital opening.^[7] Males that “sacrifice” themselves gain the benefit of increasing their paternity relative to males who do not get cannibalized since they feed the female that will lay and tend the resulting fertilized eggs.

In many other species, males are sometimes killed by females. In at least some of these cases it is likely that the males are simply mistaken as prey. The risk of this happening is greater if the female is hungry. To counter this, some male spiders offer a “bribe” to the female, in form of a fly or other prey, prior to the mating.

Ecology

Spiders have a great range of variation and lifestyle, although all are predatory.

While spiders are generalist predators, in actuality their different methods of prey capture often determine the type of prey taken. Thus web-building spiders rarely capture caterpillars, and crab spiders that ambush prey in flowers capture more bees, butterflies and some flies than other insects. Groups of families that tend to take certain types of prey because of their prey capture methods are often called guilds. A few spiders are more specialized in their prey capture. Dysdera captures and eats sowbugs, pillbugs and beetles, while pirate spiders eat only other spiders. Bolas spiders in the family Araneidae use sex pheromone analogs to capture only the males of certain moth species. Despite their generally broad prey ranges, spiders are one of the most important links in the regulation of the populations of insects.

Spider species Bagheera kiplingi, a species of jumping spiders, whose dietary habits were first discovered in 2001, obtains about 97% of its food from plant matter stolen from ants that co-exist with acacia trees in Latin America and have biochemical markers associated with herbivorious animals.^[8] Several other species of spiders sip plant nectar or eat plant spores caught in their webs early in their life cycles. All other species of spiders are overwhelmingly carnivorous.

Behavior

Spiders show a wide variety of behavior, from the ballet-like mating dances of certain jumping spiders to the seeming athletics of bolas spiders snatching their prey. Most diversity comes with the mode of predation, for example whether the spider waits for it in its orb web, or hunts it down.

Predatory techniques

Main article: Spider diversity

Although spider predatory technique is diverse, as soon as a spider makes contact with its prey, it will usually bite it.

Spiders bite their prey, and occasionally animals that cause them pain or threaten them, for two reasons: First, they inflict mechanical damage, which, in the case of a spider that is as large as or larger than its prey, can be severe. Second, they can inject venom via their hollow fangs. Many genera, such as the widow spiders, inject neurotoxins that can spread through the prey’s entire body and interfere with vital body functions. Other genera inject venom that produces tissue damage at the bite location. In the larger victims that do not die from these attacks, painful lesions over a wide area can remain for an extended time. The spitting spiders have modified their venom glands to produce a mixture of venom and sticky substance that works as glue and immobilises the prey.

Although there are no herbivore spiders, some species in the families Anyphaenidae, Corinnidae, Clubionidae, Thomisidae and Salticidae feed on plant nectar.^[9] In captivity, several spider species are also known to feed on bananas, marmalade, milk, egg yolk and sausages.^[9]

Spider webs

Main article: Spider web

Some spiders spin funnel-shaped webs; others make sheet webs; spiders like the black widow make tangled, maze-like, webs; and still others make the spiral “orb” webs that are most commonly associated with spiders. These webs may be made with sticky capture silk, or with “fluffy” capture silk, depending on the type of spider. Webs may be in a vertical plane (most orb webs), a horizontal plane (sheet webs), or at any angle in between. Most commonly found in the sheet-web spider families, some webs will have loose, irregular tangles of silk above them. These tangled obstacle courses serve to disorient and knock down flying insects, making them more vulnerable to being trapped on the web below. They may also help to protect the spider from aerial predators such as birds and wasps.

The spider, after spinning its web, will then wait on, or near, the web for a prey animal to become trapped. The spider can sense the impact and struggle of a prey animal by vibrations transmitted along the web lines.

Other species of spiders do not use webs for capturing prey directly, instead pouncing from concealment (e.g. trapdoor spiders) or running them down in open chase (e.g. wolf spiders). The net-casting spider balances the two methods of running and web-spinning in its feeding habits. This spider weaves a small net that it attaches to its front legs. It then lurks in wait for potential prey and, when such prey arrives, lunges forward to wrap its victim in the net, bite and paralyze it. Hence, this spider expends less energy catching prey than a primitive hunter such as the Wolf spider. It also avoids the energy cost of weaving a large orb-web. The diving bell spider does not use its web directly in prey capture, but has modified it into an underwater diving bell. Even species whose ancestors were building spiral orb webs have given rise to spiders who no longer make webs, for instance some Hawaiian spiny-legged spiders (genus Tetragnatha, family Tetragnathidae) have abandoned web construction entirely.

Some spiders manage to use the ’signaling snare’ technique of a web without spinning a web at all. Several types of water-dwelling spiders will rest their feet on the water’s surface in much the same manner as an orb-web user. When an insect falls onto the water and is ensnared by surface tension, the spider can detect the vibrations and run out to capture the prey.

Hunting spiders

Many spiders do not build webs for catching prey. Some examples include:

• Assassin spider
• Brazilian wandering spider
• Brown recluse spider
• Huntsman spiders
• Jumping spiders
• Lynx spiders
• Nursery web spiders
• Spitting spiders
• Tarantulas
• Wolf spiders (Lycosidae)
• Yellow sac spider

Ambush predators

Some actively lure prey (the Bolas spiders) and may capture them with a sticky ball of silk on a line; others (like the crab spiders, trapdoor spiders, or the six-eyed sand spider) wait in a high-traffic area and directly attack their prey from ambush.

Defense

Many spiders will attempt to protect themselves by biting, especially if they are unable to flee. Some tarantulas have a second kind of defense, a patch of urticating hairs, or urticating setae, on their abdomens, which is generally absent on modern spiders and Mesothelae. These ultra-fine hairs causes irritation and sometimes even allergic reactions in the attacker. Certain other species have specialized defense tactics. For example, the golden wheeling spider (Carparachne aureoflava) of the desert of Namibia escapes tarantula hawks (a species of wasp that lays its eggs in a paralyzed spider so the larvae have enough food when they hatch) by flipping onto its side and cartwheeling away.

Social spiders

Main article: Social spider

A few species of spiders that build webs live together in large colonies and show social behavior, albeit not as well evolved as in social insects. The most social species is probably Anelosimus eximius (Theridiidae), which can form colonies of up to fifty thousand individuals. Other communal spiders include several Philoponella species (Uloboridae), Agelena consociata (Agelenidae) and Mallos gregalis (Dictynidae).^[10]

Flying spiders

The peacock spider is a jumping spider with extensible flaps around its abdomen, with which it is able to glide when jumping, as well as use for mating display.

Web types

Tangleweb spiders

Members of this group (family Theridiidae) are characterized by irregular, messy-looking, tangled, three-dimensional (non-sticky) webs, also popularly known as cobwebs, generally low and anchored to the ground or floor and wall. They are commonly found in or near buildings; some build webs in bushes. The spider generally hangs in the center of its web, upside-down. Prey is generally ground-dwelling insects such as ants or crickets, in addition to small flying insects. These include the infamous black widows, the minute happyface spider, and thousands of other species.

Orb web spiders

Spiders in several families (eg., Araneidae, Tetragnathidae, Nephilidae) spin the familiar spiral snare that most people think of as the typical spider web. On average, an orb-weaving spider takes 30 minutes to an hour to weave a web. They range in size from quite large (6+ cm) to very small (<1 cm), but all are quite harmless to humans, beyond the shock entailed from walking into a face-height web and having a large spider dangling from your nose. Many of the daytime hunters have a ‘ferocious’ appearance, with spines or large ‘fangs’, but they are almost invariably inoffensive, preferring to drop on a dragline to the ground when disturbed, rather than bite, which can nevertheless be quite painful.

Other types of webs

Some (the Linyphiidae) make various forms of bowl- or dome-shaped webs with or without a flat sheet or a tangled web above or below. Some make a flat platform extending from a funnel-shaped retreat, with generally a tangle of silk above the web. The common northern hemisphere ‘funnel-web’, ‘house’ or ‘grass’ spiders are only superficially similar to the notorious Sydney funnel-web spider, and are generally considered to be quite harmless. Some of the more primitive group Atypidae may make tubular webs up the base of trees, from inside which they bite insects that land on the webbing. These spiders look quite ferocious, but are not generally considered to be particularly dangerous to humans.

Evolution

Main article: Spider evolution

Trigonotarbids, spider-like arachnids, were among the oldest known land arthropods. Like spiders, they were terrestrial, respired through book lungs, and walked on eight legs with two additional legs adapted to use around their mouth. However, they were not true spiders, not even ancestral to them, but represented independent offshoots of the Arachnida.

True spiders (thin-waisted arachnids) evolved about 400 million years ago, and were among the first species to live on land. They are distinguished by abdominal segmentation and silk producing spinnerets. The Pedipalpi (including whip scorpions) are believed to constitute the sister group to the Araneae.^[11]

Most of the early segmented fossil spiders belonged to the Mesothelae, a group of primitive spiders with the spinnerets placed underneath the middle of the abdomen, rather than at the end as in modern spiders (Opisthothelae). They were probably ground dwelling predators of other primitive arthropods. Silk may have been used simply as a protective covering for the eggs, a lining for a retreat hole, and later perhaps for simple ground sheet web and trapdoor construction.

As plant and insect life diversified so also did the spider’s use of silk. Spiders with spinnerets at the end of the abdomen (Mygalomorphae and Araneomorphae) appeared more than 250 million years ago, presumably promoting the development of more elaborate sheet and maze webs for prey capture both on ground and foliage, as well as the development of the safety dragline.

By the Jurassic, the sophisticated aerial webs of the orb weaving spiders had already developed to take advantage of the rapidly diversifying groups of insects. A spider web preserved in amber, thought to be 110 million years old, shows evidence of a perfect orb web.^{[citation needed]} It is believed that adhesive capture threads, as opposed to cribellate threads, evolved about 135 million years ago.^[12]

The ability to weave orb webs is thought to have been “lost”, and sometimes even re-evolved or evolved separately, in different breeds of spiders since its first appearance.

Taxonomy

Main article: Spider taxonomy

Araneae    Mesothelae    Opisthothelae        Mygalomorphae Araneomorphae

Almost 40,000 species of spiders (order Araneae) have been identified and are currently grouped into 111 families by arachnologists, but because of difficulties in collecting these often very minute and evasive animals, and because of many specimens stored in collections waiting to be described and classified, it is believed that up to 200,000 species may exist.

The order is composed of three suborders. In the non-venomous primitive Mesothelae, body segmentation is clearly visible, demonstrating the link of spiders with their segmented arthropod ancestors.

The two other suborders, the Mygalomorphae (trapdoor spiders, funnel-web spiders, tarantulas) and the Araneomorphae (”modern” spiders), are sometimes grouped together as Opisthothelae. The latter account for about 94% of all spider species.

Mesothelae

Main article: Mesothelae

The Mesothelae include the only recent family Liphistiidae. Two more families (Arthrolycosidae and Arthromygalidae) are recognized from fossil evidence only.

The Liphistiidae are burrowing spiders only found in Southeast Asia, China, and Japan with about 90 species in 5 genera. Spiders of this remnant suborder are very rare, and are among the most “primitive” types of spiders in existence.

Recent Mesothelae are characterized by the narrow sternum on the ventral side of the prosoma. Several plesiomorphic characters may be useful in recognizing these spiders: there are tergite plates on the dorsal side and the almost-median position of the spinnerets on the ventral side of the opisthosoma.

Mygalomorphae

Main article: Mygalomorphae

The Mygalomorphae are also called the Orthognatha, referring to the orientation of the fangs roughly in line with the body axis. This suborder includes the heavy bodied, stout legged spiders popularly known as tarantulas as well as the dangerous Australasian funnel-web spiders. They have ample venom glands that lie entirely within their chelicerae. Their chelicerae and fangs are large and powerful. Occasionally members of this suborder will even kill small fish, small mammals, etc. Most members of this suborder occur in the tropics and subtropics, but their range can extend farther toward the poles, e.g. into the southern and western regions of the United States and Canada, the northern parts of Europe and south into Argentina and Chile.

Araneomorphae

Main article: Araneomorphae

The Araneomorphae, (previously called the Labidognatha), are often known as the modern spiders.

Araneomorphae are distinguished by fangs that move at a 90 degree angle to the body axis, like a pair of pincers. Most of the spiders that people encounter in daily life belong to this suborder, which makes up 94% of all spider species.

There are approximately 95 families in this suborder, ranging from the minute Patu digua (0.37 mm) to the big and flashy Argiope, from the common orb-weaver spiders to the abstruse assassin spiders, from the reclusive tree trapdoor spiders to the inquisitive jumping spiders.

Creatures often mistaken for spiders

In addition to the true spiders, there are several arachnids commonly mistaken for spiders, but that are not true spiders.

• Camel spider, a species of solifugid (also commonly called sun-spiders or wind-scorpions), are the source of many urban legends. Although they have no venom the camel spider has been known to attack humans, focusing on exposed skin, and with fangs capable of tearing human flesh. Several myths surround camel spiders, and their size is usually exaggerated. While they are really the size of an adult human hand, myths tell they are as large as the lower half of an adult human leg. Also, they are harmless to humans, and will only attack if disturbed.
• The daddy long-legs or harvestman is a member of the order Opiliones. These round-bodied arachnids have only two eyes and their heads are fused to their bodies. However, the name “daddy long-legs” is sometimes used to refer to cellar spiders, which have a similar leg shape; these are true spiders. Both are also often said to produce a deadly venom. While the harvestmen do not produce venom at all, the cellar spider’s venom is completely harmless to humans. The term daddy long-legs is also used in British English to refer to the Crane fly, which is an insect and not an arachnid at all.

Spiders and people

Spider bites

Main article: Spider bite

Most spiders are unlikely to bite humans because they do not identify humans as prey. However, some spiders, even small ones, may bite humans when pinched. For instance, a common species of jumping spider (Family: Salticidae), around 1 cm (⅜ in) long, when pinched between the folds of a human’s palm may inflict a bite that is about as painful as a bee sting. The number of fatalities varies according to author, with some placing the yearly death toll as low as one person per year, worldwide.

Spiders in the world that have been linked to fatalities in humans, or have been shown to have potentially fatal bites by toxicology studies of their venom, include:

• The Australasian funnel-web spider
• The Brazilian wandering spider
• The recluse spiders
• The six-eyed sand spider, and possibly other spiders of genus Sicarius
• The widow spiders, including the Australian redback spider

Spiders that are never deadly to humans, but that are nonetheless medically significant include:

• Certain species of tarantulas
• The false black widows
• The yellow sac spider

Spiders that can inflict painful bites (often similar to a bee sting), but whose bites generally do not cause any systemic or long-lasting effects, include:

• The huntsman spider
• The redback jumping spider (not to be confused with the very dangerous redback spider, which is one of the widow spiders).

None of these spiders will intentionally seek out humans, but they should be removed from one’s house to avoid accidental injury. Many authorities warn against spraying poisons indiscriminately to kill all spiders, because doing so may actually remove one of the biological controls against incursions of the more dangerous species by ridding them of their competition.

If dangerous spiders are present in your area, be mindful when moving cardboard boxes and other such objects that may have become the shelter of a venomous spider. There is no need to be fearful; just do not grab a spider.

Benefits to humans

Although spiders are feared and disliked by many, they benefit humankind by destroying many insects pests such as fly, mosquitoes, grasshoppers, locusts, cockroaches, and aphids. Spiders have many medical uses such as using their venom to treat arthritis.^{[citation needed]}

Spiders as food

Spiders, especially larger sorts, are eaten routinely or as a delicacy in various parts of the world, including Cambodia, where fried spider is considered a delicacy, Thailand, the Solomon Islands, and parts of South America, where living wrapped tarantulas are also sometimes taken on trips by certain indigenous tribes.

Arachnophobia

Main article: Arachnophobia

Arachnophobia is a specific phobia, an abnormal fear of spiders. It is among the most common of phobias in certain regions of the world. The reactions of arachnophobics often seem irrational to others (and sometimes to the sufferers themselves). People with arachnophobia tend to feel uneasy in any area they believe could harbor spiders or that has visible signs of their presence, such as webs. If they see a spider they may not enter the general vicinity until they overcome the panic attack that is often associated with their phobia. They may feel humiliated if such episodes happen in the presence of peers or family members. The fear of spiders can be treated by any of general techniques suggested for specific phobias.

Arachnophobia is also the title of a 1990 film, as well as a spin-off video game, in which (fictitious) deadly spiders overrun a small California town.

Spiders in symbolism and culture

Main article: Cultural depictions of spiders

There are many references to the spider in popular culture, folklore and symbolism. The spider symbolizes patience for its hunting with web traps, and mischief and malice for its poison and the slow death this causes. It symbolizes possessiveness and storage for its spinning of its prey into a ball and taking it to its burrow (for burrowing species).

Though not all spiders spin gossamer webs, spiders have been attributed by numerous cultures with the origination of basket-weaving, knotwork, weaving, spinning and net making. Spiders are pervasive throughout folklore and mythology. Spinning and binding is evident in the etymologies of the terms religion, yoga, tantra and wyrd.

The Moche people of ancient Peru worshipped nature.^[13] They placed emphasis on animals and often depicted spiders in their art.^[14]

See also

• Endangered spiders
• Identifying spiders
• Spider diversity
• Spider-Man
• Spider webs in space

Footnotes

References

• Bilger, Burkhard. “Spider Woman”. The New Yorker, 5 March 2007, pp. 66–73.
• W. S. Bristowe (1976). The World of Spiders. Taplinger Pub Co. ISBN 0-8008-8598-8. 
• Crompton, John. The Life of the Spider, Mentor, 1950.
• Hillyard, Paul. The Book of the Spider, Random House, New York, 1994.
• Kaston, B. J. How to Know the Spiders, Dubuque, 1953.
• Main, Barbara York. Spiders, Collins (The Australian Naturalist Library), Sydney, 1976.
• Matsumoto, Toshiya (1998): Cooperative prey capture in the communal web spider, Philoponella raffray (Araneae, Uloboridae). Journal of Arachnology 26: 392–396. PDF
• Ubick, Darrell; Pierre Paquin, Paula E. Cushing, and Vincent Roth. Spiders of North America: an Identification Manual, American Arachnological Society, 2005.
• Wise, David H. “Spiders in Ecological Webs.” Cambridge University Press. Great Britain: 1993.

External links

General

• Arachnology Home Page: Araneae — Spiders
• Deutsche Arachnologische Gesellschaft e. V. — German Arachnologic Society (EN/DE)
• Indoor Spiders of New England Harvard University
• Spider info by Ed Nieuwenhuys
• Spider Pest Control Information — National Pesticide Information Center
• Venomous Arthropods chapter in EPA and UF / IFAS National Public Health Pesticide Applicator Training Manual
• Spider webs in space
• Wikia has a wiki on this subject: spiders

Regional

• Australian spiders
• Czech spiders with photos
• Portuguese spiders
• Spiders found in Great Britain
• Spiders of the Caucasus (caucasus-spiders.info)
• Spiders of Wisconsin
• University of Southern Queensland’s Find-a-spider guide
• Watson, L., and Dallwitz, M.J. 2004 onwards. The families of spiders represented in the British Isles.

Morphology

• Histology of Salticid Spiders

Taxonomy

• Canadian Arachnologist & Nearctic Spider Database
• Platnick, Norman I. (2008): The world spider catalog, version 8.5. American Museum of Natural History.
• Total number of described spider genera and species

Pictures

• Free Nature Photos, spiders
• Macro Photography - Pictures of spiders, image gallery (commercial, but very good pictures)
• Photos of spiders from around the world.
• Spiders of North America Library of reference quality large format photographs with taxonomy and descriptions.
• Tarantulas.us - Gallery — The largest photo gallery of all tarantula’s species.

Other

• Spiders Research on Spiders from Science Daily.
• Tarantula Tour
• University of California evaluations of spider bite severity
• Webs made by spiders fed on drug-dosed flies

[hide] v • d • e Spiders   Arachnology Ballooning · Behavior · Blind spiders · Cannibalism · Evolution · Classification   Taxonomy Araneomorphae · Mesothelae · Mygalomorphae · Opisthothelae · List of families of spiders · Lists of spider species   Anatomy Arthropod leg · Book lung · Cephalothorax · Chelicerae · Cheliceral fang · Cribellum · Epigyne · Exuvia · Opisthosoma · Pedipalp · Scopula · Silk · Spinneret · Urticating hair · Web · Web decorations   Human interaction Arachnophobia · Cultural depictions · Spider bite · Spider fighting   Webs Spider web · Spider webs in space

SpiDers Are beNefIcIAl

Spiders are not insects; they are arthropods, meaning they have eight legs instead of six. Spiders are beneficial predators that help control insect populations, and produce medically useful venom. Because most spiders are beneficial and not harmful, most do not need to be controlled. Some people, however, have allergic responses and severe reactions to venomous spider bites.

• Common Species and Locations
• About Spider Webs
• Life Cycle
• Control Options

Common Spider Species and Locations

Name	Description	Where Found
Name	Description	Where Found
Wolf Spider	Description	Where Found
Garden Spider	Description	Where Found
Brown Recluse	Description	Where Found
Black Widow	Description	Where Found

back to the list

 

About Spider Webs

Many spiders build geometrically concentric, highly organized silk webs. Some spiders build unorganized webs that look like diaphronous mats, and a few build no webs at all, such as the Trap Door Spider, which spins a web-like “door” over its lair which is a hole in the ground. When unwary prey step on the door, they fall to the spider waiting below.

Spider webs are spun from a special silk created in the abdomen of the spider. The spider uses special legs called spinnerettes to spin the silk into strands. The strands in which the prey become entangled are extremely sticky. The spider also makes thicker strands that are not sticky. These strands are like support beams in a building; they anchor the web, strengthen it so it can resist the struggles of prey and weather events, and they also enable the spider to travel around the web without becoming entangled in the sticky strands.

When a prey insect blunders into the web, it quickly becomes tangled in the sticky strands. Its struggles for freedom alert the very sensitive spider, which travels the non-sticky strands until it can reach the prey. The spider has two kinds of venom: a bite and a sting. The spider bites the prey to temporarily immobilize it. Then the spider quickly spins a silk cocoon around the prey until it is completely enclosed. The cocoon is then suspended in the web until the spider wishes to feed. The venom from the spider’s sting liquidizes the prey into a form the spider can consume(a type of pre-digestion). back to the list

 

Life Cycle

Spiders can’t fly. After hatching within the silk egg sack, baby spiders of many species emerge from the sack and begin spinning a silk “parachute”. This parachute carries them to new locations, where they begin hunting for insects for food. The web builders begin building webs; the trap door spiders build a door over their lairs in the ground; and a few spiders select a place where they hide and then jump upon their prey. Very little is known about how a female attracts a male when it is time to mate. Some spider species (such as the black widow) eat the male after mating is completed. After mating, the female spider spins a silk egg sack within which she deposits eggs. She will die before the eggs hatch. back to the list

 

Control Options

Since spiders are highly beneficial, they should not be killed. Leave those in the yard and garden alone to do their part in the web of life. They will help you control lawn and garden pests. In the house, the occasional spider is easily swept up into a newspaper with a broom from which it can be safely put outside where it belongs.

If spiders must be controlled due to allergies or an infestation, begin by identifying the spider involved. Locate where the spiders live and what prey is supporting the spider population. Remove all potential hiding places inside and outside buildings and improve storage practices. All small holes through screens, around doors, pipes or wires into a building must be blocked to eliminate spiders’ (and their prey’s) entrance. Control flies and fruit flies, primary prey of many spiders that inhabit buildings.

Since spiders are arthropods, not insects, they are not sensitive to some insecticides. Check the product label to see if it is effective against spiders. Insecticides may be used as needed according to label directions on the harmful spiders, their webs and on grounds immediately outside infested buildings. For all products, read and follow label directions. Start insecticide applications by spot treatment of exposed spiders, typically with a spray product, or with a dust product. If necessary to treat webs, apply dust or liquid insecticides that will leave a residual amount of product to deter rebuilding of webs. To treat perimeter grounds outside infested buildings, direct hand-held pressure sprays or “back pack” sprays are generally the product types used. back to the list

The BroWn RecLuSE sPiDer

 

Brown Recluse Spider

  SPIDERS    SPIDER ELIMINATION

Araneae: Loxascelidae, Loxosceles reclusa

Brown recluse spiders belong to a group of spiders commonly known as violin spiders or fiddle backs. This is because of a characteristic fiddle-shaped pattern they have on their head region. The spider is golden brown with the fiddle being dark brown or black. This spider is not hairy and the fiddle pattern is often shiny. They are about 1/4 to 3/4 inch long. Members of this small family are known for their poisonous venom. They have six eyes in three pairs. The cephalothorax is rather flat above and has a conspicuous, lengthwise furrow in the midline at the rear third. Each foot has two claws. Many of the wolf spiders are similar in appearance and have similar markings as the brown recluse. They are large, robust, hairy, and therefore they can be distinguished from the brown recluse.

These spiders spin small, irregular webs under bark, stones or other secluded areas. Their venom is especially poisonous to people; those bitten often become ill and find that the wound does not heal quickly. Both male and female recluse spiders, as well as their spiderlings, are capable of injecting venom which may result in serious lesion formation or systemic reactions.  The severity of the bite may vary. The symptoms may vary from no harm at all to a reaction that is quite severe.  Usually, the brown recluse spider bite is not felt and the pain sets in from six to eight hours later.  A typical bite area may resemble a pimple, postule or blister formation within six to 12 hours later.  Mild to severe pain accompanied by swelling may occur during this interval.  The surrounding tissue begins to darken, is irregular in shape with sharply raised edges resulting in a sunken area which may be several centimeters in diameter.  Often there is a systemic reaction within 24-36 hours characterized by restlessness, fever, chills, nausea, weakness, and joint pain. Where the bite occurs there is often tissue death and skin is sloughed off.   In some severe cases, a wound may develop that lasts several months.  In all cases, a physician should be notified. If at all possible, kill and take the spider to the physician for positive identification. Individual spiders can be crushed underfoot or sprayed with an aerosol spray. For more about elimination and control of recluse spiders, go to our Spider Elimination page.  Go to the Spider Products page to see breakdown of products used to control Brown Recluse and other spiders.
Bites and Stings    Brown Recluse Spider Bite 

Brown recluse spiders are found primarily in the Midwest. Many cases of bites are reported from Alabama, Florida, Georgia, Texas, Kansas, Missouri, and Oklahoma. They are suspected of being in other states as well. The edge of its range just reaches the tip of western Virginia, but it occurs rarely in this state. The spider commonly lives in basements, attics and garages of houses and often hides behind boards and boxes.   Bites often occur when the spiders hide in towels or old clothes left in those areas. The Brown Recluse has adapted quite well to indoor habitats.  They are commonly found in the storage areas of residences, including areas such as attics, closets, bedrooms and other dark recesses.  This spider frequently inhabits clothing, toys, books, boxes, furniture as well as transport trucks, tool sheds, tree houses and little used or abandoned dog houses.

The brown recluse are nocturnal and prefer foods such as firebrats, crickets, cockroaches and other soft bodied creatures.  Earning their name well, the recluse spider ceases its wanderings at first light.  People are most commonly bitten in bed, while changing clothes, or cleaning storage areas.  Not only will this spider hide in cracks and crevices of the home, they will often climb into clothing or shoes that someone has laid out to wear the following day.

Female deposits eggs in off-white silken cases about 1/3 inch in diameter in sheltered, dark areas. Spiderlings emerge in 24-36 days and abandon the egg case. Development is slow, influenced by weather conditions and food availability. They reach maturity in 10 to 12 months and can survive long periods of time without food or water.   Immature spiderlings resemble adult brown recluse spiders but have lighter coloration.  Adult males and females will vary from light tan to dark brown.

BlacK wIdOw SpIDer

Black Widow Spider

BIOLOGY OF SPIDERS     SPIDER ELIMINATION

Araneae: Theridiidae, Latrodectus mactans

The male black widow’s abdomen is more elongate than that of the female, with white and red markings on its sides. The female’s abdomen is almost spherical, usually with a red hourglass mark below or with 2 transverse red marks separated by black. The legs of the male are much longer in proportion to his body than that of the female. The female is the most easily recognized, her shiny black body giving great contrast to the red hourglass marking on her round abdomen.

The black widow’s range is from Massachusetts to Florida and west to California, Texas, Oklahoma and Kansas. Although they can be found in almost every state (and some portions of Canada), this spider is most common in the Southern locales of the United States. Black widow spiders are common around wood piles, and are frequently encountered when homeowners carry firewood into the house. Also found under eaves, in boxes, underneath unused construction materials, inside wooden toy boxes, firewood boxes, outdoor toilets, meter boxes, and other unbothered places.

The female black widow spider rarely leaves her web. The web she constructs is an irregular, tangled, cris-cross web of rather coarse silk. The core of the web is almost funnel shaped, woven into a silken tunnel in which the female spider spends the majority of her daylight hours. This web is altered and rebuilt in a regular basis and is capable of capturing rather large insects. The female wraps any captured prey with her silk, repeatedly turning her victim with her legs as she applies more silk. After her victim is covered in silk, the spider kills her prey by injecting her venom. The prey might be eaten immediately or reserved for a later feeding. After the prey is fed upon and the body fluids are sucked from the victim, the carcass is cut loose and allowed to drop to the ground. The female black widow is most often found hanging upside down in her web, where she spends most of her daytime hours. She stays close to her egg mass, defensively biting anything that disturbs her or her egg sac. After laying her eggs, the female black widow is hungry and more likely to bite a human. The female black widow stores sperm, producing more egg sacs without mating. Some females live more than three years.

Egg sacs are pear shaped (or oval), brown, papery and about ½ inch long. They hold from 25 to 900 or more eggs, which have an incubation period of 20 days. The spiderlings disperse shortly after emerging, tearing an opening in the egg sac and stay near the sac. After several hours, these second instar spiderlings balloon to the ground and scatter. Growth requires two to three months, with older females dying in autumn after egg laying.

Of all spiders, the Black Widow is the most feared. The female’s venom is especially poisonous to people. Despite its reputation, this spider often attempts to escape rather than bite, unless it is guarding an egg mass or if it is cornered and pressed. The male black widow will not bite you. After mating, the female sometimes eats the male (remember, she only has to mate once in her life), earning the name “widow.” During the period shortly following mating and laying of eggs, the female black widow can be a little cranky and hungry. After this period (if he lives through it!) the male lives quite comfortably, eating prey captured by the female. The development of his venom sacs stop and become inactive as the male matures, thus making him less of a potential problem than his female counterpart.

The bite of the female black widow spider may not always be felt at first and besides slight local swelling, there is usually little evidence of a lesion. Two tiny red spots can sometimes be observed in the center of the swollen area. Most of the time, pain at the site of the bite occurs immediately and becomes most intense after about three hours. An overall aching of the body, especially the legs, are common reactions. Headache, elevated blood pressure, nausea and profuse perspiration may occur in severe cases. The condition is self-limiting and in most cases symptoms disappear in two or three days. Calcium gluconate is used intravenously to relieve and relax muscle spasms produced by black widow venom.  (See Bites and Stings)

Be very careful when working around areas where black widow spiders may be established. Take proper precautions, wear gloves and pay attention to where you are working. Black widow bites are sharp and painful, and the victim should go to the doctor immediately for treatment. For more about control of the black widow spider, go to Spider Elimination.

rEd BacK SpiDers

Redback spiders

A redback spider has a red mark on its back.
These spiders are found everywhere in Australia.
Females make a funnel-shaped web.
Redback spiders eat insects.
Their bite is poisonous to people.

 

Habitat
Redback spiders live in most parts of Australia. The female redback builds a sticky, tangled web in dry, sheltered places. She hides in a funnel-shaped part at the top of the web. Inside logs, under rubble and rubbish, among rocks and in sheds are places where redback spiders can be found. Male redbacks do not build webs.

Appearance and Behaviours
Spiders are not insects, they are arachnids. They have 8 legs (insects have 6 legs).

Female redback spiders have shiny black bodies with an orange or red stripe on the upper abdomen. A female’s body is about the size of a large pea. Males are smaller and are brown. Their red markings are often pale. Redback spiders have long, thin legs.

Redback spiders are more common in warmer weather.

Diet
Redback spiders eat insects. Large female redbacks sometimes capture small lizards and will also steal food from the webs of other redback spiders.

Predators
Daddy-long-legs spiders and white-tailed spiders hunt and kill redback spiders.
Life cycle
The male redback spider hangs around near a female’s web. He gets the female’s attention by showing her his abdomen. This can be dangerous because if she mistakes him for prey she will squirt digestive juices onto him and try to eat him. Many males are eaten as they mate!

Once the female has mated, she can lay several batches of eggs. She produces about 10 white egg sacs, one every 3 weeks or so. Each sac contains approximately 250 eggs. These sacs hang in the web. When they hatch, the tiny, pale-green spiderlings balloon away on silk threads to another place suitable for a nest.

Female redbacks live for about two to three years. Males live for about six or seven months.

A Relative
The Black Widow Spider of the United States is a close relative of the Redback spider.

Danger to humans
Only the female redback bite is dangerous. The poison can make people sick with sweating, vomiting and pain. There is an antivenom for redback bites. No person has died from a redback’s bite since the antivenom was discovered.

Redback spiders are not aggressive, and females rarely leave the web. However caution is advised as their bite is very poisonous and could be very dangerous, even fatal, for children or the elderly.

After a bite, the there may be little pain for five minutes, but then it becomes very painful.

First Aid
Anyone bitten by a redback spider should seek medical attention. An antivenene is available and very effective.

Do not bandage the bite, but apply iced water and take simple painkillers.

The best First Aid is prevention!
Manage redback spiders by learning to recognise their webs and the kinds of places they live. Get an adult to destroy the nest and egg sacs. Spraying has only a temporary effect, and kills the natural predators that kill redbacks.

sPiDers_wHoS The ReaL HerO

Kevin Thompson

It’s a dark, stormy night. The hero is lured into an old, dilapidated and possibly haunted house. He enters the house and finds there is no electricity; his only source of light is a torch. He creeps through the huge entrance hall towards the creepy, spiral staircase. As he approaches the staircase he suddenly twitches and gets caught up and entangled in, yes, a huge spider-web.

This scenario is not only used in films, but also in books, comics and dramatised radio programmes. It always seems to touch a nerve with the audience because most people seem to have a fear or dislike of spiders. A herpetologist I know has no problem working with snakes but shudders at the thought of working with or even having to touch spiders.

Blow away the cobwebs?

One of the first things people will do when moving into a new house or after having been away, is to dust away all the cobwebs suspended from various walls and ceilings around the house. As summer approaches, they will then complain that there are too many pest insects around the house. Spiders are among the most misunderstood animals about the house and garden. Not only do they have beautiful colourings, patterns and shapes, but they also fulfil an important ecological niche and their presence should be encouraged.

Useful Allies Indeed

The jumping spider, family Salticidae, is a common visitor to homes in Arabia. These spiders often have striking patterns on their bodies and are able to jump at their prey. Just before jumping though they lay down a disc to which they attach silk thread. This acts as a ’safety harness’ so if they miss their prey, they don’t fall to the ground. Food for the jumping spider is mainly flies and mosquitoes - so they are great to have around!

Orb-web spiders, family Araneidae, will spin beautiful geometric webs between plants in order to catch their prey. These spiders are usually brightly coloured and quite striking when viewed up close. The family is divided into the garden orb web spiders, Argiopinae, and the typical orb-weavers, the Araneidae, such as the hairy field spider.

Other efficient predators found in the garden are the small crab spiders, Thomisidae. These spiders are coloured to blend in with their surroundings and are capable of catching prey larger than themselves. The prey usually being pest species such as flies.

So next time ‘the hero’ is entangled in the spider web, think about how much time and energy the spider took to make the web and how useful it would be in catching unwanted household pests. (Or the director?)

---

ALIEN INVADER

The black widow spider, Latrodectus sp., an introduced species from Australia (brought in along with shipments of wood), is amongst the few venomous spiders that can be found in Arabia. These spiders rarely exceed 1 cm in length and are usually very shy, remaining in dark, humid areas of the house or garden. They are rarely aggressive and will only bite if cornered or agitated.

However, unlike other spiders their presence in the home should not be encouraged. If a black widow spider is found, and positively identified (very important), it should be removed and killed using a broom or similar object. Do not use your bare hands. Take care to also remove the egg sac, which is a white silk ball attached to the web.

BlaCK wiDow SpIderS

Black widow spiders can be found in all four deserts of the American Southwest, including the Sonoran Desert where Phoenix is located. There are different types of widow spiders, and all of them are venomous to varying degrees.

Here in Arizona you are most likely come into contact with the L. hesperus species. You can recognize the black widow spider fairly easily: the female black widow is shiny black, usually with a reddish hourglass shape on the underside of her abdomen. Her body is about 1.5 inches long. Adult males are harmless, about half the female’s size, with smaller bodies and longer legs.

See a larger photo of a black widow spider.

 

Black Widow Spider Facts

 

• The black widow is the most venomous spider in the U.S.
• People rarely die from black widow spider bites, since the amount of venom injected is so small.
• The adult female black widow is venomous. Males and juveniles are usually harmless, having smaller quanities of venom as compared to the female.
• The female black widow spider is sometimes referred to as the “hourglass” spider because the red marking on her belly is often in the shape of an hourglass. Sometimes it may look like two triangles.
• The adult female black widow spider is often easy to see since she hangs upside down in her web, making the red hourglass marking visible.
• The female black widow sometimes eats the male spider after mating.
• There are more than 35,000 species of spiders in the world.
• The black widow spider is nocturnal, and will generally only attack when disturbed or touched.

You will find black widow spider most often in dark, hidden places, like garages, sheds, or woodpiles. Webs are usually near the ground.

The best way to keep black widow spiders away is to keep areas clean and free of webs. The spiders prey on insects like crickets and roaches, so if you regularly rid your property of insects you will have fewer black widow spiders.

If you are working around areas where black widow spiders may be established, like in piles of stored boxes in the garage, or piles of wood outside, wear gloves.

Common insecticides may or may not be helpful. Check all labels before using commercial insecticides, especially if you have small children or pets. When in doubt, contact your local exterminator.

hOw TO treAT A bLACk wiDOW SpiDer BiTes

sPidEr FacTs-SpIder SeNse By NaTioNal GeOGraPhIc

Spider Sense: Fast Facts on Extreme Arachnids

spIders By MahalO

Guide Note

Spiders are eight legged invertebrate animals classified as arachnids. There are over 100 families of spiders, comprised of over 40,000 species.¹

Fast Facts

1. Kingdom: Animalia
2. Phylum: Arthropoda
3. Subphylum: Chelicerata
4. Class: Arachnida
5. Order: Araneae
6. Have existed for over 300 million years²
7. Only 25 species have venom that affects humans³

Characteristics

Spiders have special characteristics that differentiate them from insects. These features include only two main body parts: the cephalothorax and the abdomen. Each main section has four legs. Spiders also have no antennae, as most insects do. Spiders are distinct from other arachnids by the fact that they have a small waist and tough exterior over the cephalothorax.²

Spider Myths

Contrary to what many people believe, spiders are not insects. In addition, all arachnids are not spiders. The “grandaddy longlegs,” properly known as the harvester, is not actually a spider. All spiders are not male, and they do require a male and female in order to mate.⁴

spIdErs bY MaHaLo

Guide Note

Spiders are eight legged invertebrate animals classified as arachnids. There are over 100 families of spiders, comprised of over 40,000 species.¹

Fast Facts

1. Kingdom: Animalia
2. Phylum: Arthropoda
3. Subphylum: Chelicerata
4. Class: Arachnida
5. Order: Araneae
6. Have existed for over 300 million years²
7. Only 25 species have venom that affects humans³

Characteristics

Spiders have special characteristics that differentiate them from insects. These features include only two main body parts: the cephalothorax and the abdomen. Each main section has four legs. Spiders also have no antennae, as most insects do. Spiders are distinct from other arachnids by the fact that they have a small waist and tough exterior over the cephalothorax.²

Spider Myths

Contrary to what many people believe, spiders are not insects. In addition, all arachnids are not spiders. The “grandaddy longlegs,” properly known as the harvester, is not actually a spider. All spiders are not male, and they do require a male and female in order to mate.⁴