Efficacy of insecticides to control Tegenaria agrestis and Latrodectus hesperus (Araneae: Agelenidae and Theridiidae)

Abstract:
Two spiders of possible medical importance in the Pacific Northwest were chosen for this study: the hobo spider, Tegenaria agrestis, male and female, and the black widow, Latrodectus hesperus, female. Three management strategies were investigated with chemicals applied to the substrate, spider webbing and spider directly. Three classes of chemicals were tested: Termidor® SC, a phenyl pyrazole (fipronil); Tempo® SC Ultra, a pyrethroid (cyfluthrin); and Premise® 2, a neonicotinoid (imidacloprid). Fipronil controlled 96% of the spiders after 8 days, cyfluthrin controlled 70% after 5 days and imidacloprid controlled 18% of the spiders after 14 days. A higher level of control was obtained with application of fipronil and cyfluthrin to female L. hesperus and male T. agrestis compared to female T. agrestis. Application methods showed similar results.