ULM, Germany, March 23 (UPI) -- For burying beetles, killing the mood is just as important as tending the flame.

Male burying beetles have extremely high sex drives. As researchers in Germany recently observed, they continue to try to mate with their partner throughout the egg-laying process.


Surprisingly, however, they take a brief break from sex to help raise the kids. It turns out burying beetles, Nicrophorus vespilloides, are rather progressive. Very few insects co-parent.

But what motivates the male beetle to flip the switch from seducer to caretaker?

Scientists at the University of Ulm analyzed the pheromones, or chemicals, deployed by beetles during the mating and child-rearing process. As soon as the larvae are hatched, the female beetle shuts off her egg production and sends out an anti-aphrodisiac that's received by the male's antennae.

The pheromone calms the male's sex drive and encourages him to focus his attention on his newborns.

Burying beetles are so named because they carve out a love nest in an animal carcass. When the little ones are born, all they have to do is peel a bit of rotting flesh from the wall and they've got instant baby food.

The pheromone doesn't last forever, of course. As soon as the baby beetles are big enough to fend for themselves, the female restarts her egg production and the two beetles get back to business.

The researchers, who published their findings in the journal Nature Communications, say the chemical communication is to the benefit of both parties, not just the female.

Lab observations suggest males are keenly unaware of their sexual success. Despite the fact that females are sufficiently impregnated after one or two sessions, male burying beetles have a seemingly insatiable appetite for sex. They continue to mate throughout the egg-laying process, perhaps to ensure the babies are theirs.

"It was ridiculous, because in our lab there was no one else, but the father still kept copulating, just to make sure," Sandra Steiger, an assistant professor of biology at Ulm, told the New York Times.

Sex isn't free, however. It uses valuable energy that would be wasted if males kept trying to mate after their young were already born. After all, they too are motivated by a desire to perpetuate their genetic code, and the chemical communication helps them momentarily realize their priorities -- kids.

"Only thanks to the evolution of a reliable signal of reproductive state could the common interests of both parents be realized," researchers concluded in their study.