E-408 06/12 Spiders Wizzie Brown and Mike Merchant* here’s an old naturalist’s saying that you’re Female spiders are usually larger than the males. never more than 5 feet from a spider. It’s Most spiders have eight simple eyes, though T probably true, as spiders can be found some species 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 flies and plant-feeding insects Almost all spiders bite and use venom 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 arachnids 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 arthropods, arachnids have a hard dissolve their prey’s body tissues. Spider venoms are outer exoskeleton 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 (Steatoda 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 Tarantulas producing organs called Tarantulas are among the largest spiders spinnerets. 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 tarantula (genus distinguish spiders from abdomen and eight legs. Aphonopelma) 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 jumping spider. 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 family Lycosidae, are among also release abdominal hairs 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, black, yellow, Tarantulas can make good pets. 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 pet 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. Wolf spider, crickets, mealworms, or caterpillars. Tarantulas can 4). They range ½ to 3 inches Schizocosa 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” spider web. Figure 5. Argiope spider in Argiope aurantia, 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 chelicerae, 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.