Walking through the woods the other days, I noticed some burying beetles. I didn’t have time to stop and watch them for long, but I could see that they were trying to bury a dead crow. I went back a few days later, and there was no sign of the crow apart from a few feathers.
Burying beetles are the grave-diggers of the insect world. When they find a dead animal, they set to bury it and even drag it somewhere else where the soil is easier to dig. Small animals can provide food for the adults and the larvae.
The Latin name of Nicrophorus, which means grave-digger, sums them up perfectly. Burying beetles are also known as sexton beetles. These beetles depend on the decaying bodies of dead animals for food and will also bury the carcasses to provide for their larvae.
Burying beetles are large insects ranging from 12-30mm in length. There are 68 burying beetle species worldwide, and the American burying beetle is critically endangered, with approximately 3000 alive in the wild.
Species can be found in North America, Great Britain, Europe, China, India, the Philippines, Russia, Mongolia, Kazakhstan, and many other countries.
Most have black and orange bands on the back, with some variations. You can find burying beetles wherever there is carrion or roadkill. You can find them in fields, woods, moorland, and even your garden. They are carnivores and feed on the carrion they find.
How do burying beetles find food?
Burying beetles will hibernate in winter and become active in the spring. They can be seen flying about at night, using their antennae to search for decaying flesh. They use chemoreceptors on their antennae to find their prey. Burying beetles will also eat the larvae of flies that have laid their eggs on the carcass.
There can be as many as 40-50 burying beetles on a large dead animal. They will make a small camp about a foot away from the carcass and then take turns feeding on the maggots.
On a smaller animal such as a bird or small mammal, they will first drive off other insects, including other burying beetles, not of the opposite gender.
When a partner does appear, they are welcomed, and the two will continue to repel and fight other burying beetles off. Eventually, the corpse becomes the property of a breeding pair of burying beetles. The breeding pair is generally the original pair because animals will fight in defence of their territory harder and fiercer than when trespassing on others.
The pair will then start to bury the animal, excavating under the corpse and skinning it slowly as it is dragged underground. In experiments where a string has been used to secure the corpse, the beetles will bite through the string. In an experiment where a wire was tied to the leg, the beetles amputated the leg, taking the rest of the body underground.
If the soil is too hard to dig or stony, then burying beetles have been seen to drag the corpse to a site with softer, easier to dig dirt. The beetles use their forelegs and flat heads to dig.
Below the ground
The corpse will be dragged about 10-20cm below ground. The beetles will excavate a large chamber to house the carrion and the beetles to walk around.
Once the corpse is below ground, the male beetle will leave. The female will stay in the chamber and dig a narrow burrow away from the corpse. She will then lay about 15 eggs equally spaced along the burrow.
Once back near the corpse, the female makes a circular crater in the top of the carrion and feeds for the first time since starting the chamber.
Five days after being laid, the larvae hatch. They make their way to the mortuary chamber and will climb to the crater that the female has made. They do not feed directly from the dead body as the mother feeds them a drop of brown liquid. If there are too many young, the mother will commit infanticide.
About five hours later, the larvae will start feeding on the corpse. Once they have completed one or two skin moultings, they will look to the mother to feed them again. Once they grow large enough, the mother will leave the chamber.
The larva makes a burrow about 30 cm long away from the chamber when they are satiated. Here the larva turns into a pupa and hatches into an adult beetle two weeks later.
The average lifespan for an adult burying beetle is about 12 months.
The burying beetle is essential as it returns nutrients to the earth allowing vegetation to grow while helping to keep other insect populations in check.
Burying beetles are said to be more advanced than wasps and bees due to the parental care shown by the female. Bees and wasps only provided a store of food for their young.
You may see burying beetles flying around, and as with moths, they are often attracted to light. If you want to attract them to your garden, then a small chicken body can be left in your garden for them to discover and bury.