Blister Beetle: Have You Seen This Beetle?

Jude Boucher, UConn Extension

blister beetle

The short-winged blister beetle, Meloe campanicollis is in the genus know as oil beetles, because they exude a yellowish liquid when handled.  The liquid contains cantharidin, a substance known to blister the skin when handled and is toxic to livestock.  This species is unusual in that the adult tends to feed on plants in late fall and winter.  Last fall I visited a farm that was having a problem with something feeding on their Brassica crops and leaving just the center vein of the leaves (see fig. upper right), similar to the damage that a rabbit might make.  We determined that the damage was being caused by this large (>1”) metallic-blue beetle, which the grower said had been building up on his farm for the last two or three years.  Due to the late frost last fall, there were a number of crops still growing on the farm, but the insect seemed to be targeting his Brassica crop beds exclusively, even though the different Brassica crops were interspersed  b