Chemical management strategies for the invasive Jorō spider, Trichonephila clavata (Araneae: Araneidae)

Historically, spider management has received relatively little attention in the literature compared to insect pests, and few studies have examined the efficacy of chemical management strategies on orb weaver mortality and web site fidelity. However, the introduction and rapid spread of the Jorō spider, Trichonephila clavata (L. Koch, 1878; Araneae: Araneidae), in North America has created a wave of media and public awareness. Characterized by its large size, bright coloration, dense aggregations, and durable webs, this species has garnered concern from residents who wish to manage this pest. Internet-based advice ranges from using products labeled for arthropod control to common products around the home. Our study evaluated spider mortality from eleven separate products and two control treatments (water and no treatment at all). High doses of pyrethroid pesticides or essential oil and detergent-based pesticides were highly effective in killing T. clavata. Although spraying foaming dish soap and machine lubricant also led to high mortality rates, we do not condone the use of products outside of their registered label use. We also evaluated several products that did not cause high mortality for their potential to cause T. clavata to abandon their webs-a result that may be just as desirable for residents-though none of these products led to high rates of web abandonment. We strongly recommend that property managers carefully weigh the pros and cons and safety aspects of different management strategies (including mechanical management) and assess whether T. clavata management is warranted in the first place.