Rugged oil beetle

With winter well on the way, the window of invertebrate activity is coming to a close. However, this doesn’t mean all invertebrate species. There are some hardy, resilient species out there that thrive through the winter and whose lifecycle is in line with the cold, dark, winter months. Amongst these tough bugs is the Rugged oil beetle. They are one of only five species of oil beetle found in the UK with three of those five classified as rare. Rugged oil beetles can be found from September through to April and are thought to be mainly nocturnal.

Fast Facts

Latin name: Meloe rugosus

Notable feature: Groove down its thorax

Rarity in the UK: Rare / Common

Where in the UK: Central and Southern England and Wales

Why are they called oil beetles?

Oil beetles get their name from the toxic oily secretions that they produce from their leg joints as a defence against predators when threatened.

Lifecycle

The lifecycle of an oil beetle is one of the most fascinating life cycles of any British insect as they are nest parasites of solitary mining bees. Females will dig nest burrows in the ground where they lay about 1,000 eggs, once these eggs have hatched the larvae make their way onto flowers where they put their stealth skills into action, patiently lying in wait for an unsuspecting bee to come along. Once a suitable bee has buzzed over, the oil beetle larvae use their hooked feet to grip onto the bee, catching a free ride to the bees nest. Once they have arrived at their destination, the larvae eat the bee’s eggs and the store of pollen and nectar the bees have been working hard collecting for their nest. The larvae then stay in the bee’s nest to develop until emerging as an adult ready to mate and start the cycle again.

Mistaken Identity

Rugged oil beetles are similar-looking to the Mediterranean oil beetle (Meloe mediterraneus). You will need to look closely to tell these two beetle apart – both have a rather rough appearance to their thorax, abdomen and elytra (wing cases), the Rugged oil beetle has a distinct narrow groove in the middle of its thorax, and is smaller than the Mediterranean oil beetle.

Oil beetle conservation

Oil beetles rely upon abundant populations of their bee hosts.  As our wild bees have declined due to a lack of suitable wildflower-rich habitat, oil beetles have disappeared from large parts of our countryside.  All five UK oil beetle species are considered to be conservation priorities, and Buglife is working with partners such as the National Trustand Oxford University Museum of Natural History to learn more about oil beetle ecology and help their numbers to recover.

To find out more about Rugged oil beetles and all oil beetles visit our Oil beetle species project page and to find out how you can help to conserve these important little critters visit our Oil beetle guide and Oil beetle hunt Wildlife Survey page.

Habitat

Flower-rich grasslands on chalk, limestone and sandy soils.

Did you know?

A female oil beetle can lay up to 40,000 eggs in her two month lifecycle