OUCH!!!!

Is it my imagination or is there a conspicuous lack of information available about identification, biology and control of domestic spiders? A wealth of information exists for insect and commensal rodent pests, but when the topic of spiders comes up it’s like entering a vacuum. The only spiders that receive adequate coverage are the local poisonous species - the black widow and brown recluse. How often do our customers find these spiders in their homes?

Our unfamiliarity with spiders is particularly disturbing in light of the fact that reports of spider bites in the home are frequent and occur throughout the year. Do we pass off these reports as examples of delusory parasitosis or do we investigate the problem?

I decided to look into the spider bite incidents that have been called into my company, Varment Guard, from the Columbus, Ohio, area and have arrived at some interesting findings. In nearly every instance of spider bite, there were short flat tubes of silk here and there along the junctures of walls and ceiling in the rooms of the dwellings inspected. Some of these silken tubes contained light yellow spiders, the bodies of which measured about ¼-inch long. I searched my references and keyed them as sac spiders, Chiracanthium inclusum (Hentz) and Chiracanthium mildei L. Koch (family Clubionidae). The latter of these two species was the most commonly encountered spider in this study.

Bites from these spiders have been reported from Georgia and Ohio. One bite victim described severe pain in the locality of the bite, accompanied by nausea, and experienced residual pain for three days. However, most bites result in small red marks or tracks on the skin. Such was the case for one lady I interviewed who, with calm curiosity, watched a sac spider crawl onto her forearm and proceed to bite the skin - not just one bite but a trail of bites. This person eventually became annoyed and brushed the spider off her arm. The bites felt like mild pin pricks to her and left a short track of red marks on her arm.

BEHAVIORAL CHARACTERISTICS. During warm months sac spiders can be found outside among leaves and under bark. I have seen them wandering about tree trunks and branches at night as they hunt for food. Indoors sac spiders are active all year. I have found them in my own home wandering about walls and ceilings at night. Usually my wife discovers them and promptly calls them to my attention.

Most homes I inspection in the central Ohio area are occupied by sac spiders. However, most people do not report bites from these pests. Why are some people bitten and others not? Perhaps the stimulus to bite relates to a person’s individual body chemistry. In any case, the pest control industry should approach domestic spider problems more seriously.

I have achieved satisfactory results in controlling sac spiders with applications of Ficam Plus or Commodore WP as a fine fan spray to upper corners of rooms in homes where they occur. Of course, some wall surfaces may stain; so a spray test in an inconspicuous area should precede each questionable situation.

Dr. Gerald S. Wegner is co-owner of Varment Guard, Columbus, Ohio

ACKNOWLDEGMENTS

Special thanks to Dave Dennis of the Ohio State University biology Department for photographing my specimens, and Dr. G. B. Edwards, curator of arachnida and myriapoda, Florida Department of Agriculture and Consumer Services, for his technical assistance.