Bug of the Month May 2014: Iron Cross Blister Beetles

Subject: Identifying an insect
Location: Saguaro National Park East in Tucson, Arizona
May 1, 2014 4:41 pm
While hiking in the Saguaro National Park East today, we encountered bugs that we had not seen before. They had red heads or eyes, with spotted yellow/green on their backs. The bug, itself was black underneath. They crawled at a good pace but seemed to like clinging to the small plants with leaves, possibly eating the leaves. They were about an inch in length. Today is May 1, 2014 and like I said, we had never seen them before and we hike there at least 4 times a week.
Signature: R A Kirby

Iron Cross Blister Beetles
Iron Cross Blister Beetles

Dear R A Kirby,
These are Iron Cross Blister Beetles in the genus
Tegrodera, and we generally get a few identification requests from Arizona and occasionally California each spring.  We are making this our Bug of the Month for May 2014.  The bright coloration is quite distinctive as well as being aposomatic or warning coloration.  Blister Beetles in the family Meloidae are able to secrete a compound, known as cantharadin, that might cause blistering in human skin.  The aphrodesiac Spanish Fly is made by grinding the bodies of a European Blister Beetle.  According to the Sonoran Desert Naturalist:  “Normally these beetles emerge in large numbers in mid to late spring and move together in bands crawling or running across the ground. They feed on succulent leaves and flower petals. The larva stage is subterranean and likely is parasitic in nests of ground-nesting bees.” 


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