A day out this week on the Essex coast at Wallasea with colleagues from Buglife looking for Oil Beetles. As luck would have it, we hit a warm sunny morning, with singing Corn Buntings everywhere. And plenty of the target species; Black Oil Beetles Meloe proscarabaeus, along the seawall, mostly doing what Oil Beetles need to do in the spring.. The name derives from their habit of releasing oily droplets from their joints when disturbed; this contains cantharidin, a chemical apparently causing blistering of the skin and painful swelling.
The life cycle is fascinating. The female beetle lays up to 1,000 eggs in burrows close to the burrows of mining bees. The larvae, known as triungulins, climb up into flowers and wait for a passing bee collecting pollen. They then hitch a lift on the bee back to the bee’s nest where they munch their way through the bee’s eggs and pollen supplies. The adult beetles emerge from the bee burrows after overwintering. More on the Buglife website here.