When is the best time to treat yellowjacket nests?

Treating yellowjacket nests in the spring, particularly at night, is the most effective approach for several reasons. In the spring, yellowjackets are typically in the early stages of nest development when their populations are smaller. This makes the treatment more manageable and reduces the chances of being attacked, as there are fewer workers to defend the nest vigorously.

Additionally, treating at night significantly lowers the activity level of yellowjackets, further minimizing the risk of stings to the technician performing the treatment. During this time, the wasps are less aggressive and are tucked in for the night, allowing for safer access to the nest for insecticides or other control measures.

Though yellowjackets can sometimes be treated in other seasons, such as summer or fall, the potential for higher aggression and larger populations makes these less suitable times for effective treatment. Treating in winter during a freeze is ineffective because the yellowjackets are not active and the nest is often abandoned or inactive.