WARNING – don’t read this post before eating your tea!
Recently I came across a carcass on the path on the reserve. As far as I could see it was a dead vole – reason for death unknown. But it was appearing to be very attractive…….to gravediggers.
As you can see there were about 14 black and orange beetles on, around and even in the dead vole. These are burying or sexton beetles – they are so keen on small dead mammals and birds they actually fight over who gets the chance to tidy up the carcass – they are nature’s bin men.
Sexton beetle have antennae with lumps or clubs on the end. These have chemoreceptors on them which they use to detect dead animals from a long way away. Once they have detected the carcass the race is on as they will fight male versus male and female versus female to be the couple that wins the dead thing that raise their young on.
The winning couple (trying not to think of Love Island here) then have to bury the carcass as soon as possible to hide it from other competitors.
The happy couple dig a hole under the carcass and remove all of the fur from the body. They then cover the body with an antibacterial and anti fungal secretion that slows down the rotting of the carcass and stops other competitors detecting the rotting smell. The fur that is removed is used to line the hole or crypt. The female lays eggs into the soil around the crypt and these hatch after only a few days and the larva move to the carcass.
Amazingly these beetles are great parents. They actually stick around and can feed the larva by eating the rotting carcass themselves and regurgitating liquid food for the larva to feed on and this speeds up the growth of the youngsters. The adults continue to look after the larva for several days, protecting them from other scavangers . The final stage of the larva crawls off into the soil to pupate and hatch out as an adult.
So I am not exactly sure what was happening here. Maybe this was a mass scrum of various males and females fighting it out to be the lucky couple to win the dead vole. Or sometimes several couples of can beetles work together on bigger carcasses to bury them and raise their young communally. What I do know is that this species looks to be Nicrophorus vespilloides as it has black clubs on the end of its antennae. This is one of the commonest burying beetles found in the UK.
But I do find these invertebrate life stories so fascinating and complex. Who would have thought that such a system existed for disposal of bodies? But iIt is a good thing they don’t grow to the size of sheep, thought if they did it might mean a whole new style of green burial for humans!