University of Kentucky Department of Entomology

Mystery Bug Answers

Mystery Picture #38

Mystery Picture #38

(Mystery Pictures)(Mystery Pictures)


Blister beetles often feed on flowers but groups of them can be found devouring some garden plants. Their common name comes from a protective chemical that they contain which can cause severe irritation if one is mashed on your skin.

Blister beetles are a serious problem in alfalfa if crushed and mixed into the hay during harvest. The poisonous substance in blister beetles is called cantharidin and it is as toxic as cyanide or strychnine! Horses are particularly susceptible (they can die within 72 hours of eating the toxin), but cattle and sheep feeding on hay contaminated with crushed blister beetles can also be killed.


Usually members of this group of the Lepidoptera are dark- or dingy-colored because they fly at night. Many members of the Ermine moths have white wings with black spots, hence they are named after the ermine weasel whose winter coat is white with black tips on the feet and tail. We tried to trick you with the species in this picture! It is unusual for the group in that it has brightly colored front wings and flies during the day.

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