There are many types of flying insects that lay their eggs in ponds and other freshwater habitats. These include mosquitos, gnats and non-biting midges. The eggs hatch and develop into free swimming, some of which we discovered during our pond dipping sessions. In fact one midge larva actually became a flying adult in one of our containers.
Many of these insects, such as mosquito and blood worm, can live in low oxygenated water and so they may be found in the bottom of a pond or in water sources such as water butts for collecting rainwater.
Many, like the mosquito have a larvae and pupae stage in their life cycle. The larvae stage is very active and they swim in a wiggly movement and then return to the surface. The mosquito larva (left) have a breathing tube to breathe at the surface. The larvae start off tiny and then they grow, moulting their skin 5 times.
The larvae then develop into pupae that look like a curled up form of the larva. This is a non-feeding stage and inside the pupae the adult is beginning to develop (similar to a butterfly chrysalis) but the mosquito pupa is still active.
Eventually the newly formed adult will emerge at the surface of the water. The newly emerged adult will rest on the surface of the water for a short time to allow itself to dry and all its body parts to harden. The wings have to spread out and dry properly before it can fly. This is a very vulnerable stage for the adults and many will be eaten by predators or become trapped on the surface of the water.
If you watch through the Winterbourne Stream cam, when the water level is high, you will see a swarm of midges flying above the water These adult flies will mate and soon lay eggs in the water to start a new life cycle.
Many of the adults will be eaten by insect-eating birds that are attracted to ponds and ditches in search of food. These can be an important source of food for nesting birds, including the reed warblers that nest in the heart of reeds.
The adult insects can be seen swarming low over the surface of still or slow moving water and these may be eaten by swallows and house martins that can fly low over the water to grab a flying insect.