Researchers from the University of California-Riverside suggest that many conventional pesticides may not control spiders as well as consumers intend.
Their study, published in the Journal of Economic Entomology, found that water-based pesticides — which comprise most pest-control substances used near structures — weren't very effective at controlling the invasive brown widow spider.
Although their ingredients effectively kill spider eggs and spiderlings, the brown widow's silk prevents water-based pesticides from easily reaching through its egg sac.
Female brown widows can produce many egg sacs, which contain an average of about 135 eggs according to a study of populations in southern California.
"If you want to control spiders, you have to control egg sacs, too," said co-author Rick Vetter. "And if you want to kill spider egg sac contents, you need to use an oil-based pesticide."
Oil-based aerosols, added fellow co-author Dong-Hwan Choe, were effective in providing "the complete prevention of the spider emergence."
"The public should realize that the pesticides that they purchase from the home improvement centers may not be doing the job that they want them to do," Choe said.