Today, thirteen recluse spider species can be found in a number of states located in the southern and midwestern United States. Obviously, the brown recluse species is the most well known recluse species in the country, as they are responsible for the greatest amount of medically significant envenomation cases, and they are easily the most widespread of all recluse spider species in North America. When compared to the other 12 recluse species in the US, the brown recluse is the only species that is known for regularly establishing potentially extensive infestations within homes and buildings.

The brown recluse and the non-native Mediterranean recluse are the only two recluse spider species that have been documented in Louisiana. The brown recluse is commonly encountered within and around homes in the northern half of Louisiana, specifically, from Alexandria northward. While the brown recluse is almost never encountered in southern Louisiana, the European-native Mediterranean recluse spider species has been documented numerous times within and around structures in urban areas throughout the state, but most notably in the south in and around New Orleans.

Brown recluse spiders emerge from their winter harborages during the spring season, and they become active indoors throughout the summer before returning to their overwintering sites during October. While brown recluse spiders overwinter in dark and dry locations in the natural environment, such as beneath tree bark and within wood piles, they have also learned to exploit human dwellings where they can remain active throughout the winter season. In homes and buildings, brown recluse spiders establish harborages within dark and dry enclosed areas, such as storage closets, attic spaces, cupboards, behind hanging picture frames, interior spaces of furniture, and utility boxes.

Once the daylight hours become shorter during the fall, brown recluse species retreat into cracks and crevices on walls. When it comes to eradicating brown recluse spiders that nestle within narrow wall crevices, insecticide dust applications are ideal, as dusts adhere more readily and for a longer period of time to surfaces than chemical insecticides. Obviously, insecticide dusts are also safer than chemical insecticides for treating utility boxes, wall outlets and other areas where electronic equipment is located.

Have you ever encountered a congregation of brown recluse spiders within a dark concealed area within your home?