Country diary 1918: tragic murder of the caterpillar

2 August 1918 Grubs slowly devoured their host, biting their way through the almost empty skin and pupating alongside the unhappy victimI have received from a correspondent a small natural packet of little cocoons, each neatly swathed in yellow silk and arranged side by side. He found them alongside the shrivelled skin of a caterpillar, and asks: "What tragedy has happened here?" A tragedy indeed for the caterpillar; a very useful murder so far as we are concerned. The cocoons cover the pupae of braconids, little parasitical wasps related to the useful ichneumon flies; the parent stung the caterpillar with her ovipositor, loading its living body with her eggs. Grubs hatched from the eggs, slowly devoured their host, and when it had no longer energy to feed or even crawl bit their way through the almost empty skin and pupated alongside the unhappy victim. A fresh crop of braconids will emerge from these cocoons. Related: Caterpillars create 'avenue of ghosts' in Cambridge park - in pictures Continue reading...