Female flies evolved serrated genitals that get in the way during sex

copulating flies

Awkward manoeuvres

Aya Takahashi

If female flies choose to lay their eggs in an unusual location there can be surprising knock-on effects for the shape of male fly genitals.

Spotted-wing drosophila (Drosophila suzukii), originally from Asia but now found in Europe and North America, are a major pest. While most fruit flies lay their eggs on decaying fruits, females of this species deposit theirs inside unblemished fruits including strawberries, grapes and plums. To pierce the tougher skin of ripening fruit, the females have evolved a modified version of the egg-laying organ – the “ovipositor” – which …