The most common pest problems in spring vary slightly by region, but nationwide, spring pest activity follows several common patterns.
Termite swarming is the most iconic pest event of spring — typically on the first warm, humid evening in April–May, mature termite colonies release thousands of winged reproductives (alates) that fly out to find new nesting sites.
Spring is the optimal window for preventive termite treatment — the soil is warm and moist, and the efficacy of chemical barrier treatments is at its best.
Ants awaken from their low-activity winter state in spring — worker ants begin foraging en masse to gather food for the colony's spring brood-rearing season.
Stinging insects build nests in spring — the overwintered queen awakens alone in early spring and begins building the initial starter nest; this is the safest and most effective time to spot and remove a small, nascent nest (the size of a tennis ball).
Mosquitoes — after the first warm spring rain, overwintering Aedes eggs hatch, and overwintering Culex females emerge from diapause to begin blood-feeding and egg-laying; spring is the starting point for year-round mosquito control — eliminating overwintering standing water and discarded containers is the most critical task now.
Flies — fly species that overwinter as pupae in the soil emerge as adults in spring; spring is an important time to clean up outdoor garbage and animal waste to prevent fly breeding.