Chironomus annularius (commonly known as bayfly or mufflehead) is a species of non-biting midge in the family Chironomidae.

The smaller males are at a disadvantage physically, but they can more easily latch onto females in the air to mate.

For example, C. annularius males have shorter wingspans, which causes them to produce higher frequency sounds (434±27.8 Hz).

On the other hand, females have longer wingspans, which causes them to produce lower frequency sounds (240±17.2 Hz).

[3][6] C. annularius, like many of its similar family members, gravitate towards habitats that have open bodies of fresh water and an abundance of plant life and decay.

[6][7] Macrophytes provide the flies with a place to give birth, an adequate supply of food, and shelter.

Added on to this, C. annularius stay on the outskirts of freshwater ecosystems in order to avoid areas of open water.

[10] The genus name Chironomus was decided, which was derived from the Ancient Greek word cheironomos, meaning to gesture with your hand.

[11] This followed the spirit of the family name Chironomidae, which in Ancient Greek means a pantomimist or one who entertains or dances with exaggerated hand movements.

[12] These meanings of names most likely alluded to the swarming behavior and movement of the midges belonging to the Chironomidae family.

[5] Lastly, the species name, annularius, is derived from the Latin language, with the meaning 1 year old or annual.

[13] This naming is contradictory to the life span of the adult non-biting midges (3 days to a few weeks) but may be related to the seasonable noticeability of the C. annularius, particularly in spring and fall.

There are a set of eyes or areas of pigment that lie beneath the cuticle and lastly two antennae protruding from the dorsal cranium.

Protruding from the thoracic sections are parapods, fleshy false legs that have claws at the end.

This is considered the transitional phase between the fourth instar stage and the adult imago C. annularius.

At the end of the pupal stage, the pupae leave its protective shell and swim upwards to the surface.

Their bodies are a dark brown or black color and the wing length ranges from 4 to 6 mm.

Lastly, swarming of males increases the attraction of females, because the sound of the flight tone is amplified when they band together.

These larvae feed on fine particulate organic material floating at the bottom of the body of water they were born in.

Although the species resembles its close relative the mosquito, it is a non-biting midge and does not consume blood.

[10] Multiple different species of the Chironomus genus are considered vectors of pathogens due to their blood sucking behavior.

However, the opposite can be said when they pose a negative impact by clearing all healthy algae from ponds or affecting the health of macrophytes.