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Home , Aphonopelma, Ground spider, Latrodectus, Recluse spider, Spider web, Tarantula

E-408 06/12

Spiders

Wizzie Brown and Mike Merchant*

here’s an old naturalist’s saying that you’re Female are usually larger than the males. never more than 5 feet from a . It’s Most spiders have eight simple eyes, though T probably true, as spiders can be found some have six, four, two or no eyes at nearly everywhere, indoors and out. Despite their all. The pattern and number of eyes is useful in creepy reputation, spiders are largely beneficial and identifying spiders. help keep pests like and plant-feeding insects Almost all spiders bite and use to under control. With few exceptions, spiders rarely paralyze their prey. After injecting the venom, bite and are not generally dangerous to people. the prey is often wrapped with silk to subdue it. Spiders are and are more closely Many spiders live solely on a liquid diet because the related to mites and scorpions than to insects. Like powerful digestive enzymes injected by the fangs insects and other , arachnids have a hard dissolve their prey’s body tissues. Spider are outer and jointed legs. Arachnids are being studied for possible uses in medicine and pest distinguished by having eight legs attached to the control. cephalothorax, which is the front body region and Only two types of spiders in Texas are bears the head and thorax fused together (Fig. 1). considered medically significant: the brown recluse, Male spiders Loxoceles spp., and widow spiders, Latrodectus spp. have modified palps Only a few other spiders, such as house spiders (mouthparts) which ( spp.) and sac spiders (Cheiracanthium serve as a sex organ. spp.), can produce a noticeable bite. The rear portion of a spider’s body, called Common spiders the abdomen, has silk glands and web producing organs called Tarantulas are among the largest spiders . in Texas. Despite their size and fearsome The spinnerets and reputation, tarantulas are shy and are seldom Figure 1. Ground spider a distinct abdomen showing cephalothorax, seen. The common Texas brown ( distinguish spiders from abdomen and eight legs. ) can have leg spans of more than the other arachnids. 3 inches when fully grown (Fig. 2). *Extension Program Specialist–IPM; and Professor and Extension During the day tarantulas live in burrows or in Urban Entomologist, The Texas A&M University System natural cavities under rocks or logs. The burrows are sometimes coppers. Males are lined with silk especially ornate webbing and and use their are covered colors and mating with a thin silk dances to attract curtain. In the females. winter or the Jumping hottest months spiders have Figure 2. Tarantula, Aphonopelma. of summer, excellent vision Figure 3. Adult . these burrows for hunting prey. are plugged with soil. Tarantulas rarely go far from They have eight eyes, including one large pair in the their burrow entrance; they wait for prey to come to front. They are territorial and hunt during the day. them. Tarantulas can live 5 to 30 years. As their name implies, they are excellent During mating season, male tarantulas leave jumpers. This behavior can startle observers, but the burrow in search for females and can be seen like most spiders, jumping spiders are unlikely to in yards or even by the hundreds along Texas bite unless cornered or handled. Jumping spiders highways. Females live in their burrows after put out a dragline of silk when they jump and can maturity and do not participate in these seasonal sometimes be seen dangling from this thread after a migrations. leap that fails. Tarantula bites are not dangerous. When threatened, tarantulas rise up on their hind legs and Wolf spiders wave their front legs to warn off predators. They Wolf spiders, in the Lycosidae, are among also release abdominal that can irritate skin, the most common spiders in fields and backyards. eyes or nasal passages of trespassers. They are hairy and their drab color is mottled with brown, gray, , yellow, Tarantulas can make good . Some species are or creamy white markings. easy to care for, and can become tame and safe to handle. The body hairs on the top of the abdomen They have eight eyes, with a in American tarantulas have barbs that may irritate front row of four tiny eyes in the skin, so always wash your hands after handling a straight line and a larger a tarantula. Pet stores can tell you which central pair in the hind row. species make the best pets. Wolf spiders often have two Tarantulas need a constant supply of water in a flat dark, longitudinal stripes dish filled with small pebbles into which they can on the cephalothorax (Fig. lower their mouths. They eat live insects such as Figure 4. , crickets, mealworms, or caterpillars. Tarantulas can 4). They range ½ to 3 inches spp. go for several weeks without food, and often will long. refuse to eat when they are preparing to molt, or Wolf spiders are most active after dark and shed their skin. Tarantulas can crawl up glass and have good night vision. During the summer, you escape through small openings, so house them in a can shine a flashlight into roadside grasses and see secure container. dozens of tiny pinpoints of light reflected on the wolf spiders’ enlarged pair of eyes. Jumping spiders Hundreds to thousands of wolf spiders may live in the average backyard lawn, where they feed on Jumping spiders, in the family Salticidae, are insects and small organisms. Although they may easy to distinguish from other spiders. Jumping be a nuisance, they can control other pests. Because spiders tend to be stocky and brightly colored. they are so plentiful, wolf spiders commonly enter Some have conspicuous black and white bands homes under gaps in doorways. Although some wolf on their bodies or legs (Fig.3). Common color spiders can be aggressive if handled improperly, patterns include browns, grays, black, brilliant red, they are generally not dangerous to people or pets yellow, and metallic or iridescent greens, blues, and and can usually be picked up with bare hands or

2 Wolf spiders may be confused with brown recluse the web, reducing the need to rebuild as often. spiders. However, wolf spiders typically have dark Stabilimenta also reflect UV light, which may make stripes on the cephalothorax, lack the brown the web more attractive to flying insects. recluse’s fiddle-shaped marking, and have a large Unlike jumping and wolf spiders, orbweavers pair of eyes on the top of their heads. do not see well. Instead, they use the web to get information from the environment and to locate slid onto a piece of paper and relocated outdoors. insects that are caught in the web. Prey is usually Female wolf spiders sometimes carry a round, quickly subdued by silken egg case. They carry this case until the eggs wrapping it in silk hatch. The young climb onto their mother’s back so the web is not and she carries the spiderlings with her until they destroyed. Though are ready to hunt on their own. orbweavers are Orbweaver spiders harmless to people, their large webs can be Orbweavers in the family Araneidae come in a nuisance. many shapes, colors, and sizes. Most orbweavers The black and make a vertically hanging orb web with concentric yellow garden spider, rings of silk—a “typical” . Figure 5. spider in , is Orb webs are marvels of architecture. The spider a web. common in Texas, and is the best known in the group (Fig. 5). The female’s body is more than 1 inch long and its legs are even longer. Male Argiope are often less than one fourth the Figure 6. Spinybacked Cobweb Orb web size of females and can orbweavers are common be found in the same in wooded areas. first establishes a bridge between two supports by web with the female. drifting a thread of sticky silk on the wind until it Grasshopper-sized insects are often caught and eaten catches the opposite support. After strengthening by these large spiders. the bridge, the spider uses its own weight and the Spinybacked orbweavers from the genera elastic properties of the silk to establish an initial Micrathena and Gasteracantha are distinctive spiders silk triangle. Over many trips up and down the that are common in wooded areas (Fig. 6). These supports and the central triangle, the spider spins spiders have a flattened, spiny shape that makes them additional radii to build the web scaffold on which resemble crabs. Their abdomen colors include white, the orb will be spun. Then the spider spins the orb- yellow, orange, or red. weaver’s trademark series of concentric, sticky rings. The spider uses up to seven different types of Long-jawed orbweaver spiders silk to build the web; the rings eventually trap flying The long-jawed spider, in the family prey. Tetragnathidae, is another common orbweaving Many spiders tear down and rebuild their webs spider. The name comes from their large , daily. Spiders that are active during the day do this or fangs. Their long jaws allow them to bite and work each morning. Some spiders eat the webs and secure their prey, though their venom is not recycle up to 90 percent of the material every day. considered dangerous to people. Some of the larger orbweavers, known as In recent years, long-jawed orbweavers in the Argiope spiders, weave a zipperlike seam of heavy genus Tetragnatha have built large communal silk into the web called a stabilimenta. The precise webs. These “super webs” are unusual and have function of the stabilimenta is not known. One most commonly been found near water, especially idea is that it serves as a warning to to avoid where there food sources like midges or other

3 Figure 9. Recluse spiders have six eyes arranged in three pairs. Figure 7. Lake Tawokoni State Park rangers Mike McCord (left) and Freddie Gowin (right) monitor a giant communal spider web at the park in August 2007. The retreat where they place and protect eggs. giant spider webs are rare for Texas. (Fort Worth Star- Telegram/Tom Pennington) As their name implies, recluse spiders are generally shy. They hide in cracks and crevices, which they line with silk. flying insects are Outdoors, recluse spiders are found in stacked abundant. firewood, under stones, in rock ledges, under wood stored on the ground and under the bark on dead Crab spiders trees. Indoors they live in attics, crawl spaces, and Crab spiders, living areas of the home. They prefer to hide in dry, in the family narrow crevices, under insulation, and in wall voids. , are Females lay one to two egg masses per year in common on leaves dark, sheltered areas. Brown recluse egg cases are and flowers (Fig. 8), about ⅝ inch in diameter, flat on the bottom, and and some species convex on top. Figure 8. Crab spider on a are found on the Brown recluse spiders bite when they are flower. ground. These trapped or pressed against the skin. These spiders spiders are easily recognized by the crablike way they may bite if you accidentally roll over one in a bed or hold their two front pairs of legs and the way they put on clothing that has a spider inside. Bites also scuttle sideways and backwards. These spiders do not occur when people clean garages and barns. spin a web, instead they ambush their insect prey. Recluse spider venom breaks down skin and Some crab spider species can change color to match the flower on which they are perched. One other group of spiders, spitting Potentially dangerous spiders spiders in the genus Scytodes, has a similar Recluse spiders eye arrangement Brown recluse spiders, Loxosceles reclusa, have to recluse spiders. only six eyes arranged in pairs, which differentiates Spitting spiders have them from many other spiders (Fig. 9). Adults long, spindly, banded legs and a spotted usually have a dark, violin-shaped mark on the pattern on top of the cephalothorax with the neck pointing back toward cephalothorax. The cephalothorax is raised like a the abdomen. They are usually light to dark brown dome in spitting spiders but nearly flat in recluse and have no spines on their legs. spiders. Underneath the dome, spitting spiders Recluse spiders are most active at night but can have large glands that the spiders use to produce occasionally be seen during the day. They actively silk that is propelled (spit) from the mouth to entrap prey. Spitting spiders are harmless, slow- hunt insects and other arthropods and do not use a moving, common indoor spiders. web to trap their prey. Their web is used mostly as a

4 muscle tissue at the bite location. The initial bite piles, garages, cellars, shrubbery, crawl spaces, rain may be painless and become mild to severely spouts, termite bait stations, gas and electric meters, painful 2 to 8 hours later. The bite site may also itch, and other rarely disturbed places. swell, and become tender. Black widow spiders build strong, sticky, irregular A blister usually forms about 24 hours after the webs. They typically hang upside down in the web, bite and a slow-healing lesion forms within 1 week. revealing the hourglass markings. The egg sacs are Reactions to recluse bites depend on a person’s rounded, about one-half inch long, and hang from age, health, and body chemistry and the amount the web. Females may make more than one egg sac. of venom injected. In severe cases, surgery may be Newly hatched spiderlings usually stay near the egg needed to clean the wound and minimize scarring. sac for a few days before they disperse by . Diagnosis of a recluse can be difficult Widow spiders most often bite when they are because Staphylococcus and other can cause threatened or pressed against the skin. People may similar lesions. If you think a brown recluse or other be bitten when they accidentally disturb a spider or spider has bitten you, kill the spider and take it to its web. the doctor for identification. If it is a recluse spider, Widow spider affects the nervous system. the doctor can provide the required treatment. Initially, there may be a pinprick sensation that becomes red and swollen. The bite site usually turns Widow spiders pale in the center and it is surrounded by a tender The southern black widow, , redness. and its relatives live throughout the . Within 1 to 3 hours, the person may experience Other widow species found in Texas include the moderate to intense pain throughout the body that western black widow, L. hesperus; the northern could last from 2 to 3 days. Other symptoms include black widow, L. variolus; and the brown widow, tremors, nausea, vomiting, leg cramps, abdominal L. geometricus. Coloration varies considerably pain, profuse perspiration, loss of muscle tone, and among species. increased pressure. Adult female widow spiders are typically black. Males and juveniles may have orange, red and white markings on the back and sides (Fig. 10). The Ballooning is a abdomen is rounded and the ventral region often common behavior among spiders, and has two reddish triangles that form an hourglass it typically occurs shape. Some of these spiders have irregular or on windy days. spotlike markings; others have no markings at all. Spiderlings spin Female one or more light adults average silk threads which 1½ inches long; are caught by the wind and carry the adult males are tiny spiders to new much smaller. locations. Two male Erigone spiders on a grass Widow spiders seedhead. The lower one is in a pre-ballooning have eight eyes posture ready to disperse, known as the “tip-toe” in two rows. position. (Courtesy of Rothampstead Research) Widow spiders are usually found Bites can be more dangerous for children, the in protected elderly, and people with health problems. Few cases areas outdoors have been fatal. or in structures Seek medical care for a black widow bite; the that are open to patient should be taken to a hospital emergency the outdoors. room to receive the appropriate . They may Figure 10. Female widow spider (top), male widow (bottom). live in wood

5 Move firewood or other construction items away from the house. Prune back shrubbery or trees that touch the house to discourage widow spiders from building webs on exterior walls. Outdoor lighting attracts insects and the spiders that feed on them. Direct light away from doorways where possible, and turn them off when they are not needed. Use yellow bug lights to attract fewer insects. Reducing clutter is an important way to keep spiders away. Seal all cardboard boxes in storage with durable, wide tape on all seams. Plastic containers with tight-fitting lids will also keep spiders out. Eliminate unsealed boxes. Figure 11. Harvestmen are sometimes seen in colonies, where they may bounce up and down together. Mechanical control The best way to eliminate spiders is a good hand Spider relatives vacuum. Vacuums can remove the spiders, their webs, and their egg cases. Webs and spiders can Harvestmen/daddy longlegs also be removed with a broom, cotton dust mop or Harvestmen, though closely related, are not extendable web dusters. spiders. In harvestmen, the cephalothorax and After sweeping up webs, take the mop or broom abdomen are broadly joined, creating a large, oval- outdoors and wash or rub it in grass to remove and shaped body (Fig. 11). Like spiders, harvestmen have crush any live spiders or egg cases. A water hose or eight legs that often are very long, though some have high pressure sprayer can remove webbing from short legs. Many are brown to gray, but some have under roof eaves. brighter coloration. Harmless spiders that get indoors can be Harvestmen do not have venom and cannot removed by covering them with a cup and carefully spin silk. They have a pair of glands that release a sliding a sheet of the paper underneath. Then scent when they are disturbed. turn the cup right-side up and release the spider Some harvestmen are scavengers; others feed on outdoors. Do not handle a spider unless you know small insects, fungi, or plant material. Harvestmen that it is harmless. may congregate in groups of dozens to hundreds. When they do, it is not uncommon to see the Chemical control harvestmen bob up and down when disturbed. This Spiders are usually difficult to kill with behavior may help to ward off predators. insecticides. Because spiders often live on webs above treated surfaces, it is difficult to treat them as you would crawling insects. Spiders also appear Managing spiders to tolerate conventional pesticides better than do Learn how to recognize potentially dangerous common indoor insects. Therefore, sanitation and spiders and know where they are most likely to be physical removal are the best way to manage most found. When working in spider-prone areas, wear spiders. cotton or leather gloves to reduce the chance of When chemical control is needed, synergized being bitten. pyrethrins, resmethrin, tetramethrin, deltamethrin, Sanitation and exclusion cyfluthrin, bifenthrin, lambda-cyhalothrin, and esfenvalerate can provide successful control. Always Keep spiders outside by installing or repairing follow label directions and use only products labeled weather stripping around doors and windows. for spider control. Do not use outdoor insecticides Seal and caulk around lighted doors and windows, indoors. where insects and the spiders that feed on them Spray under and around roof eaves, window gather. ledges, and porch and patio rafters. Inside, spray 6 around windows, door facings and baseboards, and lambda-cyhalothrin, esfenvalerate, and in attics, basements, and storage places. bifenthrin, generally work best against Dusts can be effective against spiders, but use spiders. them only in inaccessible areas such as wall voids • Wettable powder formulations generally and under cabinets. Do not use dusts in attic areas provide better residual control on wood, because they can harm people working in the concrete, and brick surfaces. attic or infiltrate air ducts and enter living areas. • Residual pyrethroid dusts such as cyfluthrin Powdered boric acid is not effective against spiders. or deltamethrin provide excellent control in Because spiders can be difficult to control, it inaccessible void areas. may be best to hire a pest management professional. • Brown recluse infestations are best treated Professionals have access to products and know with a combination of sanitation, residual how to effectively manage spiders. If your home sprays, and dusts in appropriate areas. is infested with brown recluse spiders, ask Storage areas, especially with cardboard any company you are considering if they have boxes or boards, are commonly infested experience with this pest. by recluse spiders. Sealing boxes with tape reduces the harborage areas and reduces First aid for spider bites the risk of transporting spiders to other locations. Treat spider bites by applying an ice pack to • Aerosol fogs are generally ineffective for all relieve local swelling and pain. If the reaction but exposed spiders, but they may provide is severe, consult a doctor immediately and, a useful supplement to residual sprays and if possible, take along the spider for positive dusts in controlling brown recluse spiders. identification. Specific antivenom is sometimes available to treat widow spider bites. Tips for professionals • Advanced generation pyrethroids, such as cyfluthrin, deltamethrin, cypermethrin,

Acknowledgments The authors wish to thank Alejandro Calixto, Allen Dean, Jared Ripple and Sonja Swiger for review of this manuscript.

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