With desert locusts, you get two insects for the price of one. For most of their lives, they are positively antisocial and will avoid other locusts – a far cry from the devastating swarms that farmers fear. Only when the climate is right and food is abundant do they lose their solitary streak. Their numbers increase to the point of overcrowding and that flicks a chemical switch which changes their bodies and behaviour. Within 2 hours, the solitary, green locusts transform into extremely sociable, yellow or red versions that gather in voracious swarms, several billion strong.

The transformation is a complicated one – it involves over 500 genes, the presence of other locusts and stimulation of their hind legs.