The best season and time to treat yellowjacket nests are which?

• A. Spring, day
• B. Summer, night
• C. Winter, morning
• D. Spring, night

Answer: (D)

Treat yellowjacket nests most effectively when the nest is small and the colony is least active, which happens in spring and at night. In spring, the nest has fewer wasps to defend it, so a targeted application is more likely to reach the nest interior and be effective. At night, most workers are inside the nest and less active, reducing the chance of stings and making the insecticide treatment safer and more likely to stay where it’s needed. In contrast, treating in summer means a larger, more defensive colony, increasing danger and making control harder, while winter often means little or no active colony. Morning is less ideal than night because some activity can resume at first light.