Midge Larvae

• Phylulm Arthropoda (Jointed Legs)
• Class Insecta (Six Legs)
• Order Diptera ("Two Wings" or True Flies)
• Family Chironomidae

Other Names

• Blood worm (larvae with red haemoglobin)
• Fish fly (adult)
• Gnat (adult)
• Chironomids

Larvae Appearance Colours range from red, green to clear The body is thin, worm-like, slightly curved and segmented Both ends of the body are about the same shape The head is distinct and dark Two pairs of prolegs - just behind the head and at the back end of the body There may be brushes or tufts on the back end The gut is visible as a thin, dark line through the transparent body

Larvae Behavior

• Very active
• Wriggle by bringing both ends together and then springing them apart
• Live in fine sediments in the river bottom where there is less current and lower oxygen levels

Larvae Feeding Types

• Omnivores
• Consume small organisms, decaying matter and algae
• Gatherers, collectors or scavengers

Adult Appearance Casual observers can mistake adult midges for mosquitoes with fuzzy antennae Midges are fragile Midges do not have a proboscis and do not bite Swarms hover in great numbers at head height Large swarms form visible, smoke-like clouds Numbers and biomass make them the most abundant insect in many areas

Adult Behavior

• Fly in huge swarms near water
• Cyclists riding through flying clouds of mating midges with they'd worn sunglasses, long-sleeved shirts and kept their mouths closed!
• Attracted to lights
• Most adults no not feed
• Live for less than a week

Aquatic Habitat

• Still or quiet water
• River bottom and mud

Reproduction

• Life cycle includes egg, larvae, pupae and adult stages
• The males swarm in vast mating clouds while waiting for females to appear
• Male swarms move in unison back and forth over a small area
• Males "landmark" or fly in clouds over some unusual part of the landscape
• Cyclists using paved pathways along water may ride through swarms of adult midges. The insects end-up in the annoyed cyclist's eyes, nose, mouth and stick to clothing and skin.
• About 500 eggs are laid on the water in a group (raft)

Predation

• Adult and immature midges are important fish food
• Up to 2000 pupae have been counted in the stomach of a rainbow trout
• Present in huge numbers - up to 50% of the invertebrates present in some samples

Larval Pollution Tolerance

• Pollution tolerant
• Large numbers may indicate poor water quality and organic enrichment
• Larvae can survive low oxygen levels
• The transparent bodies of some midge larvae allow body fluid haemoglobin to show as a red colour, hence the nickname "bloodworm"
• Haemoglobin is a respiratory aid adapted for life in polluted water or water with a low dissolved oxygen content