Weevils wreaking havoc at Women’s Park

Have you noticed any Purple Coneflower heads (Echinacea purpurea) that are overturned on the stem and drooping head-down? The Women's Park volunteers have noticed these "clipped heads" for several years, but this year almost half the flowers suffered. After some careful examination and being tipped off by a walker that there was a weevil doing this, we found that the culprit was the adult sunflower head-clipping weevil (Haplorhynchites aeneus Boheman).

This shiny black weevil can sometimes be seen under newly clipped heads. The female is responsible for feeding on the stem until the head overturns. At this point the male and female mate and the female lays eggs in the head. The dead heads fall off in the fall and the new insects burrow about 6 inches into the soil to wait for summer when they emerge as adults.

We don't use pesticides at the Women's Park so the volunteers are trying to interrupt the life cycle of the pest by removing the dead heads and either freezing them for a few days or "cooking" them in black plastic bags in the sun for a few weeks and then putting them into the trash. We double bag to be sure they can't escape. We hope to see much less damage next year. These insects also infest sunflowers and silphium varieties – compass plant, prairie dock, and cup plant. Their season is about finished but removing heads now may protect next year's blooms.

Macy Reynolds - Women's Park Volunteer