Residual Effect of Insecticide Treatment Plus Use of Sticky Traps on Brown Recluse Spiders (Araneae: Sicariidae) on Two Surfaces

There is a need for safe and consistent management of the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, a toxic spider found in homes throughout Kansas and the south and central United States. This study examined the efficacy of two general-use insecticides with brown recluse on their labels, .05% bifenthrin with 0.0125% zeta-cypermethrin (Insecticide 1), and 0.03% lambda-cyhalothrin (Insecticide 2) against the brown recluse spider at three times post-treatment, 1, 24, and 96 hr, and on two substrates, carpet and tile. This study also evaluated the efficacy of these insecticides on spiders exposed for three lengths of time, 0.5, 1, and 30 min on each substrate. Results indicate that Insecticide 2 had better overall residual efficacy than Insecticide 1. In addition, in one experiment efficacy was better when the spiders were exposed on tile surfaces. Residual efficacy for Insecticide 2 was greater one and 24 hr after application but decreased at 96 hr. The efficacy of Insecticide 1 was not affected by length of time between application and spider exposure, on either surface. Spider mortality was also significantly impacted by the length of time the spiders were exposed to the treated surface. There was no significant difference in spider mortality with either insecticide at 0.5 or 1 min exposure. However, exposures of 30 min led to significantly greater spider mortality for both insecticides, and on both substrates. 100% mortality occurred when spiders were exposed to either insecticide for 30 min on tile. This study also examined the effect of sticky traps placed in homes and in combination with an insecticide application of 0.03% lambda-cyhalothrin. The sticky traps alone did not reduce the infestation but, in combination with one insecticide treatment, spider trap numbers decreased over a 4 wk period.