Brown Recluse Spider, No. 28
Your Extension Experts
April 2, 2015
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December 5, 2014
Although they also occur outdoors, brown recluse spiders are common, though most unwelcomed, year-round residents of many Mississippi homes, and some homes and buildings can harbor heavy infestations. Brown recluse bites are rarely life-threatening but are seriously venomous, potentially resulting in localized disintegration of tissue around the bite site, and require medical attention. Brown recluses have a distinct, dark-brown fiddle shape in the center of their backs, and this character along with the fact that they only have six eyes, arranged in three pairs, while most other spiders have eight eyes, makes them fairly easy to identify. Brown recluses are relatively long-lived, taking from 9 to 14 months to develop from egg to adult and living for several months after becoming adults. They do not use webs to catch their prey, but they do build small white webs to protect egg sacs or to serve as refuges in the dark cracks and crevices where they prefer to hide.
Control: Systematic decluttering and cleaning is the most important step in controlling heavy brown recluse infestations. This means methodically going through each room, closet, box, item of furniture and storage area to declutter, thoroughly vacuum, and apply insecticides where appropriate. Don’t underestimate the importance of thorough vacuuming to successful spider control. Be sure to vacuum backs and undersides of furniture and remove drawers from dressers, chests of drawers, and night stands and vacuum the interior of the carcass. Baseboards, crown molding, bed frames, box springs, backs of pictures, wall hangings, curtains, and window treatments also need to be cleaned. The time to apply insecticides is after the room has been decluttered and vacuumed and before everything is put back in place. Wettable powder insecticides containing active ingredients such as cypermethrin or cyfluthrin are some of the best treatments for spider control, but be sure to use according to label directions. Hiring a professional pest control company can be extremely helpful when attempting to control a heavy brown recluse infestation, but homeowners will still need to assist with the necessary decluttering and vacuuming. Results of brown recluse control efforts are strongly dependent on the amount of time and effort spent decluttering and vacuuming.
See Extension Publication 2154, Spiders, Brown Recluse and Black Widow for more information, including recommended insecticide treatments.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.