Kali Zammit, Schmit, Rene A.
It is not unusual to find spiders in homes during warmer weather, although they may be found most any time of the year. A spider here or there does not mean an invasion of spiders is at hand since spiders, for the most part, are a common occurrence in Louisiana homes. Regardless of what kind of spider you may encounter whether large or small, dangerous or harmless, the presence of any spider and especially more than one inside or outside the home is often intolerable. As it is difficult to eradicate all spiders from the home an effective control can be achieved with an integrated approach involving non-chemical methods and use of appropriate insecticides.
One of the main considerations to controlling spiders in and outside the home is to reduce or modify their stationary habitats. For indoors, this can be accomplished by removing stacked papers, cardboard boxes, paper bags, and placing items for storage in sealed containers or plastic bags. Since spiders require a regular water source to survive, eliminating water leaks, especially in the kitchen, bathroom and laundry areas of the house will discourage spiders to locate there. Populations of spiders and their ability to feed and multiply can be affected greatly by destroying spider webs, egg sacs and the spiders themselves when found. Because spiders prefer dark, damp sites avoid leaving any bedding, especially any wet towels or wet clothing stacked for long periods of time where spiders can crawl into them. For controlling spiders outdoors, locate bricks, building materials, firewood, compost piles, and other debris well away from the house. Also remove any excess vegetation such as ivy and weeds that provide a safe unexposed haven for spiders. Trim back any shrubs, tree limbs or other plants that come into direct contact with the home structure. Ensure that all window screens fit tightly and caulk or seal obvious cracks or spaces around all windows and doors.
Pre-mixed and ready to use “Home Defense” insecticides that contain bifenthrin, cyflurthrin, permethrin, or tetramethrin are readily available for the do-it-yourself consumer and are effective in controlling spiders in and outside the home. Spray applications should be made to corners and other dark areas of the house where spiders tend to hide and breed. Outside the home, spray applications should be directed under the eaves of the roof, along the base of the foundation, behind shutters and around doors and windows. Always make sure when purchasing an insecticide for indoor application that the label denotes “safe for indoor use.”As all spiders have venom, many are incapable of piercing human skin. For that reason, the majority of spiders found in Louisiana are harmless. The exception would be the black widow, brown widow and brown recluse spiders. If by chance an encounter with a spider results in a bite, the American Red Cross recommends applying an antiseptic around the bite, including an ice pack to the affected area and promptly consulting a medical physician.