The Black oil beetle Meloe proscarabaeus is a beetle that I’ve looked for on Salisbury Plain before but not found until just recently. It gets its name from its habit of secreting droplets of ‘oil’ from its knee joints when roughly handled. This contains the odourless and colourless toxic chemical compound cantharidin which can cause blistering.
There used to be eight species in the UK but sadly three of them are now considered extinct. In fact two of our remaining five, the short-necked oil beetle Meloe brevicollis, last recorded in 1948, and the Mediterranean oil beetle Meloe mediterraneus, last recorded in 1906, were also thought to be extinct but were recently rediscovered by amateur entomologists in Devon.