About the Chironomid
|Back to Aquatic Trout Food Menu|
Order Diptera, Family ChironomidaeChironomids (pronunciation: kira-no-mid) are probably best known as gnats. Their larvae are also called bloodworms or midges, and the adults are often called buzzers. They are the most important food source for trout in this province.
What do chironomids look like?
Adult chironomids look like mosquitoes with feathery antenna. They range from 2 to 25 millimeters in size through all stages of their lives - quite a variety in size.
Chironomid larva have segmented bodies, are worm-like and look much like a long skinny grub. Larva may be a variety of colours from cream to black, but they are very often bright red.
The chironomid pupa develop an eye-spot and wing casing and have feathery white gills near the head. The pupa are black, brown, reddish-brown or green but can come in many other colors.
Food for Thought... The midge larva is often called a bloodworm. Why do you think that is?
Where do chironomids live?
Free swimming larva, like the bloodworm, do just that. They crawl, float or swim around the lake but generally tend to hide under rocks or rotting logs and remain fairly immobile. Most larva build and stay inside a mud tube on the lake bottom and don't move very far from that. Chironimids will live pretty much anywhere that they can find food. They will live in both salt and fresh water and in clean or polluted water. There are many different species and sub species and it is believed that they live the world over
What is the life cycle of the chironomid?
Most chironomids have a one-year life cycle. Click here to see the life cycle of a chironomid. After the female lays her eggs on the surface of the lake the eggs sink and settle in the mud at the bottom of a lake. Once the larva of the midge hatches (this stage is also called a bloodworm), it will build itself a tube out of mud to live in. As the larva develops and grows it may molt up to six times (lose its outer skin, like a snake does).
Once it is a mature larva, the midge will seal up the tube and begin to change into a pupa. This change may take several weeks. After this transformation is complete, the pupa wiggles out of the tube and begins to rise to the surface of the lake. The upward voyage is helped by air trapped beneath the pupa's skin. The midge pupa wiggles its body upwards, keeping its head up and tail down. Once it reaches the surface, the pupa skin breaks open and the adult crawls onto the surface of the water. The process of breaking open the pupal skin, the adult crawling out, drying its wings and flying away usually takes less than a minute. The adult midge then flies off to mate. Adults swarm and mate in flight. The females return to lay eggs on the surface of the water and the life cycle is complete. Adult midges may live a few hours or up to two months before they mate. Once the female lays her eggs she dies.
Thought... Often a glass bead or some fine silver wrap is used when tying a
pupa larva fly. What is this trying to imitate?
More Food for Thought... Trout love eating chironomid pupae, even though they are small and a lot are needed for a meal. Why do you think trout love them so much?
Teacher Support Materials for this Section