I think my first introduction to the circle of life was from the highly accurate nature documentary Disney film, The Lion King. Animals are born, they grow, they breed and they die. But if this is the case, why do we not see more dead animals lying around? It’s because, just like us, nature has its own industrious group of undertakers and refuse collectors – the scavengers and detritivores. These are animals that feed on dead and decaying matter. They play an important role, recycling nutrients back into the ecosystem.

The burying beetles of the genus Nicrophorus are a particularly charismatic bunch of recyclers. There are six resident species of Nicrophorus in the UK, but I have spent seven years researching one burying beetle in particular – Nicrophorus vespilloides. Whenever I run a training session on burying beetles, I start by asking who in the room has ever seen one. The answer is often no one, which may seem surprising given the adults are bright orange and black, common in UK woodlands, and found between April and October. But their lifestyle is elusive. They spend much of their lives underground. When they do emerge to find a mate or a snack, they’re most likely to do so at dusk.

The right side of rotten

Burying beetles can sense the heady aroma of decomposing flesh using their highly sensitive antennae. If the wind is travelling in the right direction, they can locate a carcass from a mile away. You may not expect an insect that breeds on carrion to be fussy, but they’re quite discerning when it comes to their breeding resource. They can detect the exact stage of decomposition, based on the specific scent profile a carcass is emitting. When choosing a corpse for breeding, they seek out relatively fresh ones.

Fights breaks out if multiple beetles arrive at once. Males fight males and females fight females until one pair reigns supreme over the carcass. They then set to work preparing their bounty into an edible nest. Although small, they are incredibly strong. They will drag the carcass onto a suitable area of soft ground, tear off its fur or feathers, spread it with antimicrobial fluids from their mouth and anus, and roll it into a sphere, which they bury underground.

As if the preparation of this carcass nest doesn’t sound tiring enough, all through the process the pair mates repeatedly and the female lays her eggs in the soil surrounding the nest. The parents remain at the carcass for a few days to feed their hatchling larvae with regurgitated meat and defend them from intruders, until they’re big and strong enough to wriggle off to find a good place to pupate alone. About three weeks later they’ll emerge as adults, and the whole cycle starts again.

Carrion care

The process described above is the most common breeding behaviour, but a particularly fascinating feature of Nicrophorus vespilloides is that parental care is variable. If the parents die or desert after nest preparation, the larvae can often feed themselves and may still survive.

Sometimes males and females mate away from a carcass. Then if the female finds one by herself she will prepare it, use stored sperm to lay fertile eggs and provide care on her own. Sometimes if a carcass is particularly large, you may even find multiple pairs tolerating each other’s presence and breeding on the same resource.

This variation in parental care means that they have become a focus for behavioural ecology and evolutionary biology research. Why does parental care evolve? How do parents decide how much care to give their offspring? What role does conflict between parents play in care? All these questions, and more, have been investigated using this humble beetle that is busily working away under your feet during your woodland walk.

See them for yourself

If all this talk of corpses has given you an appetite for finding some beetles, how best to start? Firstly, something that seems completely normal to me, but alarming to my non-ecologist friends – if you see a small dead rodent, turn it over with your foot or a stick to check whether any burying beetles (or other insects) are toiling away inside.

If you want to take your interest to the next level, you could also put out a trap to attract carrion-loving insects. For research, we use specially designed traps. But if you’re just doing it for interest, you can go all “Blue Peter” on the situation. Start by finding some bait – either a freshly dead rodent you stumble across (but please wear gloves and wash your hands afterwards!) or a piece of offal from the butchers. Next, take a large plastic drink bottle and cut it about two-thirds of the way up. Place your carrion or offal in the bottom section on top of about 5 cm of soil. Then invert the top part of the bottle and fit it snugly inside the bottom, creating a funnel shape.

Set your homemade trap outside (in your own garden or with landowner permission) and check on it every day over the next week. Carrion insects, like burying beetles, will be lured in by the meat, but the design will make it tricky for them to escape. Once you’ve captured some, head to the Silphidae Recording Scheme website, where there’s a fantastic identification key for all UK Silphidae (the family that burying beetles sit within). There are also details on how you can submit records of your sightings to the scheme to add to our understanding of beetle distribution, ecology and population trends in the UK.

When you’re done, let the beetles go – it’s time for them to fly off to continue their role in the circle of life.