Margined Blister Beetle

bug identification
I sent a picture of these bugs the other day-then I read your message about location! I am in Blue Mound, IL which is in the heartland of the Midwest. THese bugs are devouring my green bean leafs and beans. In these photos, they are feeding! I would like to know what they are-are they any benefit to anything at all? Thanks,

Hi Marla,
This is a Margined Blister Beetle, Epicauta funebris. Since we are artists and not entomologists, we are permitted to have whacky theories about insects without worrying about seeming ridiculous to our peers. Many Blister Beetles are found in areas of arid climate. We have pondered the unusual life cycle of Blister Beetles for some time now. When the adult Blister Beetles appear, it is often in great numbers, and their ravenous appetites cause them to defoliate plants. The immature Blister Beetles do not compete with adults for food as the larvae of many genera feed on the eggs of grasshoppers. Grasshoppers would compete with the adult Blister Beetles for food in areas where food is scarce, so the larvae are helping to reduce the population of insects that compete for food with the adults. Thank you for writing back with your location.

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