Aloha Devra
Could it be a chinese rose beetle?
They riddle a leaf with round holes, usually in dry weather.
Phil

Aloha KonaPhil. Thanks for responding.

I think they might be Chinese Rose Beetles, except in all the photos I've seen of them, the shell looks smooth. These are the same color and shape, but the shell texture is uneven. They all look like that. Also, they were feeding on my plants in hot sunny daylight, whereas C. R. beetles come out at dusk or dark.

I called my county's agricultural extension, and they were stumped. They want me to plant more corn and see if the beetles appear again. They'd like me to send in samples.

This is turning out to be an interesting mystery!

aloha Kathy

Your right, Chinese Rose beetles come out only at dusk or night. Sevin would probably get rid of them or if like me you like environmentaly safe spray, try NEEM Oil.

It would be interesting to know what kind of beetle it is.

good luck

Phil