Pear Midge is quite a serious pest of pears, and there is no effective chemical control of which we are aware. Any applied chemicals would gave to be applied when blossoms are open, therefore destroying beneficial insects at same time. In hot weather in particular, the pear midge will congregate in large numbers.
The small pear fruitlets start to turn black soon after blossom drop, and then fall to the ground. If you open one of these pears, then you will find a small maggots of the Pear Midge - creamy coloured and just a few millimetre long
The fruit turning black is normally the first sign of the pear midge problem.
The Pear Midge lives life as a pupa in the soil over winter. The midge then emerge from the ground in early spring - just around the time of pear flower buds are starting to form in tight clusters. The eggs are laid in the flower and the emerging larvae finds home in the developing pear fruitlet.
Chemicals which are available commercially are not allowed for the private gardener. The best way of dealing with the pear midge, is to collect the fallen and damaged fruits and destroy. It is also thought that cultivating the soil around the trunk of the pear tree gives some degree of control to the overwintered pupae.