Brown Recluse Spider Bites

Reports of brown recluse outside this range?

The brown recluse spider is often reported from outside its natural range based only are on wounds (no specimen to identify) and many slow-healing necrotic wounds have been mistakenly blamed on this spider. Within its home range, however, the brown recluse spider can be very common and abundant but authenticated bites are relatively rare.

Like other wandering/hunting spiders brown recluse spiders are sometimes found associated with packing materials and shipped goods. For this reason lone spiders will occasionally be found elsewhere. It is highly unlikely that these displaced spiders will survive and colonize the new area.

Brown recluse spider venom

Brown recluse spiders have very small fangs and cannot bite through clothing so most bites occur when the spider is accidentally pressed against bare skin. Initially the bite is painless but sometime later (1-8 hours) the area becomes tender, red and swollen, and many bites heal without further complications. Some bites, however, progress to serious necrotic wounds that can develop into dangerous medical conditions especially in individuals with a compromised immune system. Wounds tend to be localized skin lesions that are slow to heal and eventually leave a deep scar. Many conditions mimic brown recluse spider bites and some, such as diabetes, can exacerbation the injury.

Spray for brown recluse spiders?

Not indoors. Spiders are very difficult to treat with conventional insecticides especially for homeowners because they move so readily from area to area. Plus, I believe it is unwise to apply conventional insecticides indoors where you are continuously exposed to these materials. A better approach is to use spider traps (see Making and Using Spider Traps). Purchase or make traps and continue trapping until you no longer catch spiders on a daily bases. On rare occasions it may make sense to treat an area of known heavy infestation if it is located away from the living area such as an attic or crawlspace.

However, insecticide applied to the exterior foundation below the siding ("perimeter spray") may prevent spiders from migrating into the livings areas. Onslaught Microencapsulated Insecticide is approved for this treatment (see a current label for approved uses).