· by Michael Blair, Nashville's Pest Control
The brown recluse is native to the central United States and Middle Tennessee is squarely inside its range. Older houses with attics, crawl spaces, closets full of stored boxes and gaps around the plumbing are exactly the habitat it prefers. It is a shy spider, it bites rarely and only when pressed against skin, but an established population in a house is worth taking seriously, and it responds poorly to the usual spray-and-hope approach.
Identifying one
A brown recluse is a uniform tan to brown, about the size of a quarter with its legs spread, with a darker violin-shaped mark on the back of the front body section, the neck of the violin pointing toward the abdomen. The legs are plain, without bands or spines. The abdomen is a single color with no pattern. It has six eyes arranged in three pairs, which is the definitive feature but needs a magnifier to see.
Spiders commonly mistaken for it include wolf spiders, which are larger, hairier and patterned; funnel weavers, which have banded legs and build sheet webs in corners; and the cellar spiders with very long thin legs. A brown spider with any pattern on its abdomen or bands on its legs is not a recluse.
Where they live in a house
Recluses are nocturnal hunters that spend the day in tight, dry, undisturbed places: behind baseboards and picture frames, in stored cardboard boxes, under insulation in the attic, inside wall voids, behind the water heater, in the folds of clothing left on the floor and in shoes. They spin an irregular retreat web in those spots rather than a web to catch prey.
They move between those spaces along the edges of rooms and through the gaps around pipes and wiring. A house with a lot of them almost always has a large population in the attic or crawl space feeding the rooms below, which is why treating the living space alone has little lasting effect.
Why spraying alone disappoints
A recluse walking across a treated surface picks up very little product, because it walks on the tips of its feet and grooms rarely. Residual sprays that control ants and roaches well are far less effective against spiders in general and recluses in particular. A perimeter spray reassures the homeowner and has little effect on the population in the attic.
What works is a combination. Glue boards along baseboards, behind furniture, in closets and the attic catch the spiders as they travel and, just as usefully, show where they are coming from. Dust formulations applied into wall voids, the attic and around penetrations reach the harborages a spray cannot. Direct treatment of the retreat sites found by inspection, and a reduction in clutter so there are fewer places to hide, do the rest.
- Glue boards to monitor and to catch travelers
- Dusts into voids, the attic and around pipe penetrations
- Reduce cardboard and clutter, especially in closets and the attic
- Seal gaps around plumbing, wiring and baseboards
Living with them in the meantime
Bites happen when a spider is trapped against skin: in a bed, in a shoe, in a towel or clothing on the floor. Shaking out shoes and clothing that has been on the floor, keeping beds away from walls with bedding off the floor, and storing things in sealed plastic rather than cardboard removes most of the risk while a population is being brought down.
A bite that becomes an expanding sore or is accompanied by fever needs a doctor, and it helps to bring the spider if it was caught. Most bites attributed to recluses are something else entirely, but the real thing is worth ruling out.