Tropical wasps attack intruders with unfamiliar faces

Many insect species can tell family members by the colony-specific scent they bear, but the new study reveals a sophisticated interplay between sight and scent in the nest mate recognition of this insect. When the wasps had only visual information they were more likely to accidently attack a friend and when they had only odours they were more likely to misidentify an enemy as a friend. They appeared to err on the side of caution and prioritise whether or not they recognised the face of another wasp when deciding whether to attack. This leads to wasps occasionally starting to attack others from their colony before realising their error and backing off before they cause any injury.

Dr David Baracchi, research fellow at QMUL and one the paper's authors, said: "These wasps can use both face recognition and scent to determine whether another wasp is friend or foe. Unfortunately neither sight nor smell is infallible so they appear to not take any chances and attack anyone whose face they don't recognise."

Professor Lars Chittka, another author of the study, commented: "These findings about individual face recognition in wasps add to a number of recent discoveries about the remarkable behavioural and cognitive sophistication in the tiny-brained social insects."

This study, published in Proceedings of the Royal Society B, is the first demonstrating that identification of colony intruders is mediated by the unfamiliarity of their faces. For the first time, the authors examined both visual and odour recognition in wasps, adding to our understanding of how animals prioritise different senses.