Beetle on lawn
Location: Bowie, MD
March 31, 2012 12:20 pm
My daughter’s (besides being totally creeped out by them) would like to know what this was.
Signature: Dan Delaney
The large beetle is a Blister Beetle called an Oil Beetle in the genus Meloe, most likely a female. The smaller beetles are a different species, and we suspect they are not even in the Blister Beetle family. Blister Beetles exude a compound known as cantharidin as a defense mechanism. Chatharidin can cause blistering in skin. The other beetles might be Soldier Beetles, and they do not have a chemical defense. They might be harvesting the cantharidin to use since they cannot produce the compound. We will keep trying to identify the other beetles.
Update: March 31, 2012
Thanks to a comment from Mike, we are happy to learn that these are most likely Fire Colored Beetles, though BugGuide does not provide any explanation for this behavior. We also found a photo of Pedilus terminalus on Meloe posted to BugGuide and the behavior is explained here on BugGuide.