Five species of recluse spiders have been recorded in Texas: Loxosceles apachae, L. blanda, L. devia, L. reclusa and L. rufescens. Although only L. reclusa and L. rufescens have been recorded as venomous to people, it is best to consider all these species as potentially dangerous.
The best-known species, the brown recluse spider, Loxosceles reclusa, inhabits many Southern and Midwestern states. Recluse spiders are frequently found in garages, firewood piles, cluttered cellars and stored board piles. They often live around human dwellings, in bathrooms, bedrooms and closets, under furniture, behind baseboards and door facings, or in corners and crevices. Recluse spiders are most active at night when they hunt. People are sometimes bitten while asleep, apparently when rolling over on a spider while in bed. Others are bitten when putting on clothes that have hung undisturbed for a long time and where spiders are hiding.
Description and life cycle
As their name implies, recluse spiders are generally shy. They spin nondescript white or grayish webs, where they may hide during the day. They are predators of insects and other arthropods, known to wander around houses looking for prey. While walking, their body and legs together cover an area about the size of a quarter or half-dollar, but the body itself is only 1/4 to 1/2 inch long. Their color varies from orange-yellow to dark brown.
The brown recluse’s most distinguishing characteristics are its eye pattern and markings on the back. Recluse spiders have six eyes arranged in three pairs in a semicircle on the forepart of the head. Uncommon in spiders, this eye pattern helps separate recluse spiders from similar species. The eyes also form the base of a violin-shaped marking on the back. The neck of the “violin” forms a distinct, short median groove (see Figure 1). The violin marking may be conspicuous or blend with the background color.
One other group of spiders, the spitting spiders, Scytodes, has a similar eye arrangement. A spitting spider has long, spindly, banded legs and a spotted pattern on its cephalothorax, the front body region. The cephalothorax is raised in spitting spiders but nearly flat in recluse spiders. Slow-moving, spitting spiders are common in window sills and considered harmless.
Brown recluse spiders lay one to two egg masses per year in dark, sheltered areas. Similar to those of many other spiders, recluse egg cases are round, about 5/8 inch (1.6 cm) in diameter, flat on the bottom and convex on top. After 24 to 36 days, an average of 50 spiderlings emerge from the egg case. Their slow development is influenced greatly by nutrition and environmental conditions.
The effects of a recluse spider bite may be immediate or delayed, depending on the amount of venom injected and the victim’s sensitivity. Sometimes hardly noticed at first, the bite later causes a stinging sensation that may include intense pain. Fever, chills, nausea, weakness, restlessness and/or joint pain occur within 24 to 36 hours. The bite also produces a small blister surrounded by a large congested and swollen area. The venom usually kills the affected tissue, which gradually sloughs away and exposes underlying tissues. The edges around the wound thicken, while the exposed center fills with dense scar tissue. Healing may take six to eight weeks, often leaving a scar, depending on the amount of venom injected and the reaction of the individual.
undefinedThe southern black widow, Latrodectus mactans, and its relatives live across the entire United States. Other widow species found in Texas are the western black widow, L. hesperus; the northern black widow, L. variolus; and probably the brown widow, L. geometricus. Their coloration varies considerably. For proper identification, an expert may be needed to examine mature specimens.
Widow spiders are found in protected cavities outdoors. Around houses, they may live in privies, garages, cellars, furniture, shrubbery, ventilators, rain spouts, gas and electric meters and other undisturbed places. Widow spiders also may be seen in cotton fields and occasionally vegetable gardens.
Like most spiders, widow spiders are shy and retiring. People are bitten occasionally when they accidentally disturb a hidden spider or its web. To avoid hidden spiders, take care when putting on seldom-worn shoes or clothing.
Description and life cycle
Widow spiders are typically jet black, but their color can vary considerably. Males and juveniles tend to show more color, with orange, red and white markings on the back and sides. On the underside of their rounded abdomen are two reddish triangles that may be united to form an hourglass shape.
Some individuals have irregular or spot-like markings; others have none at all. Adult widow spiders average 11/2 inches long and have eight eyes in two rows, a common spider pattern.
Females lay eggs in a loosely woven cup of silk. The 1/2-inch-long oval egg sacs hold from 25 to 900 or more eggs, which incubate for about 20 days, depending on temperature and time of year. Spiderlings usually stay near the egg sac for a few days after they emerge, when cannibalism is prevalent. Surviving spiderlings disperse by “ballooning.” They spin a single silk thread which is caught by the wind, which carries them to a new location. When about one-third grown, they establish themselves in a protected place and build loosely woven webs.
The spiders usually remain in their rather coarse, irregular, tangled webs for the rest of their lives. Over time they extend their webs and capture progressively larger prey. Males eventually leave their webs to find females for mating. Contrary to popular belief, most females do not normally eat the males after mating. This habit, found in a few species of widow spiders from other areas, gives the group its name.
If noticed at all, a widow spider bite may feel like a pin prick. Usually the bite location is indicated by a slight local swelling and two red spots surrounded by redness. The reaction is systemic and pain becomes intense in one to three hours, continuing for up to 48 hours. Symptoms include tremors, nausea, vomiting, leg cramps, abdominal pain, profuse perspiration, loss of muscle tone and rise in blood pressure. The toxin can also cause breathing difficulties and sometimes unconsciousness. However, less than 5% of people bitten by widow spiders die.
Other common spiders
Tarantulas in Texas are members of the hairy mygalomorph family in the genus Aphonopelma. These large, hairy spiders are brown to black and more than 3 inches long when full-grown. Females, larger than males, have abdomens about the size of a quarter.
Tarantulas hunt at night and spend the day under rocks, in abandoned mouse burrows or in other sheltered areas. They may be seen in the evening or late at night along country roads or trails. Migrating male tarantulas can be commonly seen for a few weeks in early summer. This migration’s purpose is not completely understood, but it may occur as males seek mates.
Tarantulas are sometimes kept as pets and can become quite tame. Although they can be handled, be careful, because they can quickly become disturbed and pierce the skin with their fangs on the chelicerae. The hair on some tarantulas may irritate the skin, so take care when handling them.
Tarantulas need a constant supply of water in a flat dish into which they can lower their mouths. They eat live crickets, mealworms, caterpillars or other insects and can go for several weeks without food, sometimes refusing to eat before molting. Tarantulas can crawl up glass and escape through small openings, so they must be kept in a container with a good lid.
undefinedWolf spiders hunt at night. Usually brown and black, they may have longitudinal stripes. Wolf spiders are large and often seen under lights. They can be seen at night when their eyes reflect light from a flashlight, headlamp or car headlight.
Members of the genera Rabidosa and Hogna are some of the most conspicuous wolf spiders. They form webbing only to provide daytime shelter, not to capture prey. Many wolf spider females carry their egg masses below their abdomens until after the eggs hatch. Young spiderlings cling to the mother’s abdomen for a short time after hatching. Wolf spiders frequently enter homes and backyards but pose no danger to people.
• As a precautionary measure, become familiar with what poisonous spiders look like and how they act.
• Because spiders nest in quiet, undisturbed areas, discourage them by cleaning and vacuuming closets, cellars and other such areas frequently.
• Seal buildings with caulk, screening and weather stripping to keep spiders from entering.
• Tape or seal boxes, especially in storage areas infested with brown recluse spiders.
• Where possible, wash off outside areas, particularly under roof eaves, with a water hose.
• Mechanically removing the webbing may be necessary because no chemical treatment to dissolve webs is available.
• When chemical control is needed, use products containing diazinon, chlorpyrifos, propoxur, bendiocarb, synergized pyrethrins, carbaryl, resmethrin, tetramethrin, malathion or mixtures of these insecticides. Always follow label directions and use only products labeled for spider control or for use in areas where spiders are found. Spray or dust outside under roof eaves, window ledges and porch and patio roofs. Inside, spray around windows, door facings and baseboards and in attics basements and storage places. Chemical control may not always be as successful as desired because spiders are mobile and may migrate back into the area. Also, species that sit on the web may not pick up much residual pesticide.
• Because some spiders, such as the brown recluse, can be difficult to control, homeowners may wish to engage a professional pest control operator.