Wednesday, 29 March 2017


The old music hall joke goes:
I used attract women like flies, but then, who needs women like flies?

Black headed gulls midge-fishing at Paxton Pits.
We are just about to enter our busiest period in terms of wildlife and visitors too. The warmer weather brings out the crowds and also the midges!

The big swarms of midges that gather near the lakes are almost all non-biters. The larvae live in the mud at the bottom of the lake but they swim upwards to the surface to hatch, which is when the gulls and terns pick them off the water. On a spring evening the Heronry Lakes form the stage for a twilight ballet performed by hundreds of white birds turning, dipping and rising, as if to a flowing melody that we can’t hear.
Mating flight of midges
As the swarms gather above the trees, swallows, swifts and martins swoop through them. Even hobbies, whose main diet is dragonflies, join in, catching midges with their feet. In the nearby trees, warblers and other small birds glean the flies from the leaves. As it gets dark the local bats will take their turn too.

As the wind drops the crowds of midges form into columns that can look like plumes of rising smoke. Each column uses a reference point to keep station, like aircraft gathering over a beacon. They may use a branch on a tree, a signpost, telegraph pole or fence post. They may even gather over your hat.

The swarm is composed mostly of females who are dancing to attract a partner. The males have feather-like antennae that detect female hormones from down-wind and they fly in to grab a mate in their big hairy arms.  But they are not the only flies to be attracted to female midges.

St. Mark's fly
St Mark’s Day is on April 25th and that’s when we should expect to see a Bibionid fly called St Mark’s fly. Fishermen call them Hawthorn Flies because they gather around the flowering bushes. These are predatory flies that look a bit like large, black midges, which makes it easy for them to invade the mating swarms and get a good meal. They have long, dangly back legs which they use to grip their prey.

Midges are the plankton of Paxton Pits, the basis of our food chain, so next time you breath in a lungful of them, try and remember that.