D3357: Insecticide-infused hydrogel baits to control European earwigs in citrus

European earwig, Forficula auricularia L. (Dermaptera: Forficulidae), is an omnivorous insect commonly found in California citrus orchards. While often considered a beneficial predator, it can also damage young fruit and defoliate young citrus trees. Laboratory and field studies were conducted in 2024 and 2025 to evaluate the efficacy of insecticide-infused hydrogel baits for earwig management. Polyacrylamide hydrogel beads were soaked in thiamethoxam or spinosad solutions at full label rate, 0.5×, and 0.1× rates, each prepared with or without 25% sucrose. In the laboratory, ~3 cc of treated hydrogel was placed in plastic containers with field-collected earwigs, with or without lemon leaves (choice and non-choice tests). Results from this trial showed that earwig mortality increased over time (12–144 h) across all concentrations and insecticides in both choice and non-choice tests compared to the control. For the field trial, ~20 cc of hydrogel was applied per tree using trunk wrap. The number of earwigs per tree was significantly reduced in all insecticide treatments compared to the control at 6 and 14 days posttreatment. Similarly, another laboratory study conducted in 2025 with and without sugar added to hydrogel showed no significant differences in earwig mortality. These results suggest insecticide-infused hydrogel baits, regardless of sugar content, may be a promising tool for managing F. auricularia in citrus.