Termite workers don’t get to peacefully retire. As they age and their bodies can work no more, some of them are fitted with suicide backpacks and conscripted for war.

There are thousands of termite species, and many engage in chemical warfare. Some squirt noxious chemicals from nozzles on their heads. Others violently rupture their own bodies to release sticky immobilising fluids, sacrificing themselves for the good of their sisters. Their range of weapons is astounding, and Jan Sobotnik from the Academy of Sciences of the Czech Republic and Thomas Bourguignon from the Université Libre de Bruxelles have just found a new one.

They were studying the termite Neocapritermes taracua when he noticed that some workers have a pair of dark