This is a very large and varied order of insects. It includes the daddy long-legs, the house fly and the many kinds of midges that can cause so much annoyance and discomfort when you are trying to enjoy the countryside on a calm day, as well as the colourful and quite harmless hoverflies.
The Diptera get their scientific name from the fact that they have just two wings, whereas most of the insects in other orders have four wings; however, there are some exceptions and so not all flies with two wings are members of the order Diptera.
As they are a major source of food for trout in stillwaters (and in many rivers), chironomid 'buzzer' midges are used here to illustrate the fascinating life cycle of insects in this order.
The worm-like larvae of chironomid midges live in decaying matter on the bed of a lake or in the slack water margins of a river. They come in colours ranging from olive and brown through red and purple to black. From the red larva comes the popular name 'bloodworm'.
In lakes and reservoirs, chironomid larvae inhabit water up to twenty feet deep. Often the best hatches come from these deeper areas, particularly on warm summer evenings.
When a bloodworm pupates, the winged adult forms rapidly inside a pupal case. Within a day or two the midge pupa has a relatively large, ginger-coloured 'head'.
When fully formed, the pupa rises towards the surface, where it may rest in the film until eventually the pupal case splits open and the adult fly emerges.
Once out of their pupal shucks, adult midges leave the surface rapidly. Adult imitations that are the right size and general colour give very good fishing results, and so matching these insects more closely (to species level) is quite unnecessary.