Natural pest controllers

Can tiny parasitic wasps help to save our conker trees?

Believe it or not there are dozens of different kinds of tiny wasps (only distantly related to the stinging wasps that we are so familiar with) that attack the horse-chestnut leaf-miner. These wasps are so small that they lay their eggs inside the leaf-miner which is living inside the horse-chestnut leaf! The developing wasp larvae eat the leaf-miner from the inside out and then burst out of the caterpillar, in the process killing it and so acting as a natural pest controller.

Can these potential pest controllers actually help by parasitising enough of the leaf-miners to control it's numbers? Answering this question was the aim of the Mission: Pest Controllers, which ran from 2010-2013.

The simple answer to the question appears to be 'no'. The number of pest controllers that people found was low - under 10% of the leaf-mines were attacked by these parasitic wasps.