OIL BEETLES
Oil beetles are incredible insects, but they are also under threat. Three of the UK's native oil beetles
are now extinct, and the remaining five species have suffered drastic declines in their distributions
due to change in the way our countryside is managed.
The five remaining UK species are ;Black oil beetle (Meloe proscarabaeus), Violet oil beetle (Meloe
violaceus), Rugged oils beetle (Meloe rugosus), Short-neck oil beetle (Meloe brevicollis) and Mediterranean
oil beetle (Meloe mediterraneus).
The short necked oil beetle was thought extinct until it was recently rediscovered at a site in South
Devon, and on the Isle of Coll in Scotland.
The Mediterranean oil beetle was although extinct until rediscovered by this project in 2012,
Oil beetles are reliant on solitary bees to complete their life-cycles. The health of oil beetle
population is therefore dependent on the health and diversity of wild bees.
The ideal habitat for beetles species is wildflower-rich grassland-a habitat that has declined in quality and
quantity due to intensive management of the countryside. Oil beetles are sensitive to change in land
management and are a good indicator of the health of our countryside.
They rely on solidarity mining of bees to complex their life cycles. Adult oils beetles feed on the leaves
and petals of flowering plants and grasses.
The female beetles are larger than males and become much larger when their abdomens become swollen
with eggs.
The adult beetles search for a mate and the female selects a suitable place to dig a nest.
The female beetle must lay a lot of eggs to ensure that enough larvae make it through their complex life
cycle, they can lay up to 100 eggs, usally in 2-3 burrows dug into the soil near to where there are bees
digging their own nests burrows.
The eggs hatch into leggy larvae known as triungulins. These larvae are very active and for a good reason
-in order to survive and reach maturity they must immediately find a bee and hitch a ride on its back.
To have the best chance of meeting a bee, the larvae climb up flower stems and lay in wait with a flower.
A solitary bee collecting nectar and pollen for its own nest may unwittingly become covered in the oil
beetles larvae, secured by their specially-adapted hooked feet.
Once inside the bee's nest, the triungulin disembarks and begins to feed on the bee's eggs and the store
of pollen and nectar. The larvae developes in the bee burrow until it emerges as an adult oils beetle ready
to mate and start the whole cycle again.
Oil beetle on bee.
