Oil Beetle, Meloe family

Several black beetles have been brought into the Home and Garden Center for identification during the last few weeks. They usually appear on the lawn in groups of 20 or more. They are in the Meloidae family, commonly called the Blister Beetle family due to their ability to emit an oily substance from leg joints when disturbed. Another name for them is Oil Beetles. The ‘oil’ contains the chemical cantharidin that will cause a painful blister on skin.

The adult is unable to fly due to its shortened elytra, and unfunctional wings. The adults feed on grass and  several leafy weeds and flowers. The larva feed on  larva  of insects,  mainly in underground nests of the host.  There are many several different species of Meloe beetles with each one preferring a different host food as prey.  The larva develop in bees’ nests where they eat the bee larva and food store’s of the bees. The female of oil beetles is larger than the male , as seen in the photo above.

Oil beetles are not considered a bad thing in the garden or lawn. They cause little damage to plants and the larva can control other pest insects. Although I would not want to see these guys in or near a hive of bees if I was a beekeeper!

-Carol Quish