Arizona Recluse spiders rest in attics, crawl spaces, basements, wall voids, upholstered furniture, clothing, among items stored in cardboard boxes indoors and under stones in warm climates outdoors. Brown spiders prey on small, soft-bodied insects. They may entangle live prey on a small mat of sticky silk or they may wander at night (also dimly lit rooms during the day) and utilize recently-killed insects as food. Sicariids exhibit continuous development in warm climates and indoors. In northern climates, they may overwinter as eggs, immature or adults in protective settings.
Arizona Recluse spiders may invade buildings from outdoors in warm weather and within their species range. They may also be carried into buildings in boxes, furniture and rolled carpets any time of the year. The bite is not painful but the venom is a potent cytotoxin, causing an enlarging necrotic sore that heals with difficulty.
Like their relatives the cobweb spiders, hourglass spiders also known as black widow, Brown Widow, and northern widow rest upside-down in their small to medium-sized irregular webs or hide in corners or crevices at the web’s edge in recessed corners of structures. Outbuildings, sheds, pump and meter enclosures commonly are occupied, as are larger rodent bait stations at building foundation perimeters. Some species build webs under rocks, in hollow trees stumps and among tree bark. Females (larger than males) deposit their eggs in round or submarine mine-shaped silk sacs, within the web.
The bite is similar to a pin-prick and the potent neurotoxin venom causes severe muscle cramping, fever and nausea which persist for a day or two. Death rarely results.
Funnel weavers (Hobo Spider, Barn Funnelweaver, Grass Spider) rest inside the tubular corner of their funnel-shaped webs during the day. At dusk, the spiders place themselves on the outer triangular sheet-like portion of the webs. Webs may be found close to building foundations outdoors on shrubs, ivy, tall grass, decks, and in window wells and recessed vents. Indoors, webs are found in the corners of garages, basements and crawlspaces. On occasion, relocating females and males searching for mates may be found wandering about or resting beneath items on basement and garage floors. Funnelweavers overwinter as eggs in the wild; however, development and activity may be observed indoors, year-round.
“The bite is similar to a pin-prick or bee sting and the cytotoxin venom of some species may cause necrotic skin lesions. Secondary bacterial infections from bites are possible.”
Tarantulas in the U.S. live on the ground and in burrows. They hunt at dusk by sense of touch. Tarantulas spin mats of silk and may line their burrows with silk. They prey on insects, other arthropods, small reptiles, young mice and are most commonly found in early fall. Tarantulas are long-lived (especially females) and survive cold weather in protective settings as juveniles and adults.
Occasionally tarantulas enter open structures and may be found under landscaping features. They defend themselves by “throwing” hairs (quickly rubbing urticating setae from the abdomen using the hind legs), assuming a threatening posture (with forelegs, pedipalps and chelicerae uplifted menacingly), lunging and biting. The bite can be painful but the venom (of U.S. species) is not considered to be dangerous. Secondary bacterial infections from bites are possible.
Cobweb spiders or house spiders rest upside-down in the middle of their small to medium-sized irregular webs in corners of porticos, eaves, garages, windows and all indoor areas. Some species hide in a corner or crevice at the web’s edge. Females (larger than males) deposit their eggs in brown, papery silk sacs within the web. Depending on species and climate, theridiids may overwinter as eggs, immature or adults. Continuous development has been observed in warm climates and indoors.
The bite is similar to a pin-prick and, except for the related hourglass spiders.
Wolf spiders actively hunt for prey on the ground and rest beneath stones and debris. Females carry their round, white egg sacs protectively attached to the spinnerets. Hatchling spiders ride piggy-back on their mother until old enough to fend for themselves. Wolf spiders may overwinter as eggs, immature or adults in the wild. Activity may persist through winter indoors.
Depending on the species, the bite is similar to a pin-prick or bee sting but the venom usually is not dangerous to humans. Temporary numbness or secondary bacterial infections from bites may occur.