Thanks to all of you who provided feedback. I would love to respond to each of you individually, but the volume of responses makes that unrealistic.
Your comments indicated that this pest weevil was indeed was fairly prominent in the Miami Valley area. Gardeners were finding it from Champaign County to Hamilton and from Clark and Greene counties on the east side to Preble and Darke on the west.
Again, to reiterate, the sunflower-clipping weevil chews the stems on coneflowers, sunflowers and other plants in this family, leaving the stems weak. The flower heads then droop and harbor the weevils’ larval development.
Best control method is to remove the clipped flowers and drop them in a bucket of soapy water.
Some of you even found the weevil itself and sent photos. Many thought that the damage was done by deer, rabbits, birds or other critters. I kind of got a kick out of the fact that these guys were blamed.
Several inquired about how long to keep it in the bucket of soapy water. Basically you are drowning it, so leave the bucket sitting around for a few hours and it should do the trick. If they are no longer moving, they are then safe to put into the compost pile.
Another common question was about predators that might feed on these weevils. At this time, I am not aware of any predators.
Many said that they had used pesticide to no avail. I hope that now you understand why pesticides don’t work: The weevil stays in the clipped head and is fairly protected.
In addition, this is a great example of what I really emphasize when it comes to integrated pest management strategies: Make sure you identify the pest causing the damage prior to using any chemicals.
Many readers said they have noticed them for a few years. In addition, one reader has been dropping the infested heads in a bucket of soapy water and has indeed noticed that populations have declined.
A great question came from Terrie C., who asked if she should not plant sunflowers in the same spot the next year. It’s a great question, because as long as you keep providing their food source they will continue to develop.
It’s likely Terrie that you will see this damage for a few more years until you can either eradicate the insect or the populations decline naturally.
I would still go ahead and plant them and keep an eye on them, because I love having these plants in my yard. You can try moving them to another spot in the yard and see if this helps.
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