Ant larvae are fighters. When ant nests are invaded by parasitic ants that hope to wipe out the original residents, larvae may try to protect their family by eating the invader’s eggs.

Some species of ant can’t build their own nests, so they attempt steal other ants’ homes. Once mated, the queen will look for a potential host nest and sneak in to kill the host queen .

Once in, the parasitic queen mimics the scent of the host species to trick the host worker ants into taking care of her eggs. As new parasitic ants hatch they also mimic the host colony’s scent, hoping they will go unnoticed until the whole nest is replaced with the parasitic species.

However, worker ants aren’t always fooled by this deception and will kill any ants they recognise as outsiders.

Eva Schultner at the University of Regensburg in Germany and her colleagues wondered if ants have a secondary defense mechanism besides worker ants. So, the team collected 424 larvae of formica fusca , a common host ant species, and placed them each onto a parasitic ant egg. Another 56 host larvae were put onto eggs of their own kind.

Within 48 hours, the team found the larvae had eaten 11 per cent of the parasitic ant eggs while all host eggs were still intact. This could suggest that larvae may do the same in the nest when a parasitic ant attempts to infiltrate the colony.

“Offspring are often overlooked in studies because we tend to think they are not powerful,” says Schultner.

The success rate of the egg eating tactic seems to be low, so it’s unclear how effective it actually is at getting rid of all the invaders. Additionally, it’s not known if larvae do the same thing in the wild as was seen in the experiment.

Journal reference: Proceedings of the Royal Society B: Biological Sciences , DOI: 10.1098/rspb.2018.2867