Catching moths in a light trap doesn’t always have the desired result. Not only moths are attracted to light, but, depending on the time of year, other flying creatures often turn up, some welcome – some not.
There are almost always midges and, in summer, wasps and daddy long legs, but this spring I have been plagued by huge black beetles.
One night I had 6 moths and 12 of these big beasties with torpedo-shaped bodies and distinct orange clubs on the ends of their antennae.
They are burying beetles, often called sexton beetles, and provide a valuable undertaking service in the countryside.
Most have orange markings on their wing cases with the exception of this particular species which is all black.
Using their highly sensitive antennae, the beetles can fly long distances to locate carrion, presumably attracted by smell.
When the beetles find a small carcass, they creep underneath and excavate the soil below, pushing it to the sides and using their jaws to cut away obstacles, such as grass roots.
In this way the dead mouse or bird slowly sinks into the earth until it is completely buried.
The female beetle lays her eggs in the soil, close to the buried carcass, and remains there until the eggs hatch.
There appears to be some degree of parental care, in that the female beetle regurgitates a brown liquid of partly digested food for the young larvae, until they are large enough to eat the carrion on their own.
The fully grown larvae burrow into the soil to pupate, away from the remains of the carcass (if any), and eventually emerge as new adult beetles to start the cycle over again.
After I had liberated these unwanted guests from my trap (which is basically a plastic bucket with a light on top), the smell inside was almost unbearable.
I have often noticed that if you flip them over, they are quite often infested with tiny reddish-brown mites.
They are gamasid mites, which cluster between the body segments, under the wing-cases and anywhere else that the beetle cannot easily reach with its legs to dislodge them.
The mites are thought to suck fluid from the beetles but this activity seems relatively harmless and many of them may be just ‘hitching a ride’ as the beetles fly off to new habitats in search of carrion.
The same or similar mites are also associated with many of the large flying scarab or dung beetles and heavy infestations are often found on the young queens of some bumblebees.
Despite their many unpleasant qualities, these seldom-seen undertakers provide an important service and is the main reason we seldom find dead birds and rodents in the countryside.