What’s your plan for dealing with the beetles? Cukes and rasberry vinaigrette sounds great. Serendipity sounds like a good corn to try.
First is identifying them for future reference.
Second is getting the sunflowers harvested and threshed ASAP, while the losses are still minimal.
Third is “treat” the seeds with a week bleach or alcohol solution to kill any eggs on them prior to storage.
Fourth, give, as planned, the threshed-out heads to the chickens and let them deal with any bugs. I’ll store them in a tightly covered container to prevent escape while they’re being doled out.
The strange thing is, we’ve never seen these beetles before; and the native prairie sunflowers have never shown any signs of this type of attack. The eggs must have been in or on the seeds.