What are midges/mayflies?

Chironomids - “May Flies” or “Non-Biting Midges” 

Each spring, massive swarms of tiny bugs emerge at Pigeon Lake. These bugs have been commonly referred to as “may flies” since this is typically the month in which they are seen in greatest abundance following their seasonal hatch. These bugs belong to a family called chironomidae, which is made up of a very diverse collection of species, each with unique features and environmental requirements. 

As the term “non-biting midges” suggests, these insects do not bite! While these insects look similar to mosquitoes, they have different body parts which prevent them from being able to bite. 

They also do not carry disease or pose any harm beyond being a nuisance as a result of their swarming behaviour. These insects also pose a significant importance to the food web, as well as being an indicator of lake health status! 

Chironomidae biology:

Chironomids undergo a 4 stage life cycle: egg, larva, pupa, and adult midge. 

Larva: The larval stage is sometimes referred to as “bloodworms” due to the red colour the worms possess from hemolymph (similar to hemoglobin in mammalian blood). These larvae occupy the sediment at the bottom of the lake, feeding on organic material and nutrients. As every species has different requirements, you will find different species depending on the conditions present at the sedimentary lake floor. 

Pupa: As the larvae transition into adulthood, they enter a pupal stage. In this stage, the insects slowly rise up to the surface. This stage is a very important food source for fish! Once the pupa reaches the surface the adult stage emerges. 

Adult midge stage: midges are the flying insect, mature form of chironomidae. This stage is only 3-5 days long before the insect dies. This stage also generally does not eat, but rather swarm for mating, then females return to the water to lay their eggs. The adult stage provides food for birds (particularly swallows and purple martins), as well as bats. When adult midges land on the water surface, they also can be consumed by fish in this life stage. 

Importance of chironomidae: 

Chironomidae are very important for the food web, providing a food source for birds, bats, and fish! When chironomidae consume organic material in the lake bed, they contribute to nutrient cycling, returning the nutrients to the food web rather than being deposited in the lake sediment indefinitely. 

Since chironomids have such specific parameters they can survive in, the species present in an area can be used as an indicator of the conditions at the lake sediment bed. For example, a species that requires high oxygen being found in an area indicates that oxygen levels are at least at this species minimum requirement. 

Managing Swarms: 

Due to the short life span of adult midges and the constant hatch of new individuals, pesticides are ineffective against chironomidae. In addition, since these insects are such an important part of the food web, usage of pesticides would have consequences affecting other species which consume them. 

To reduce frustration from swarming midges, spend time outdoors during the midday, when midges are less active. Midges are also very weak fliers, so a fan can help keep midges out of your space when outdoors. Fly veils (such as the ones used by beekeepers) can also help you enjoy time outdoors while these insects are present.

Conclusion: While these massive swarms of insects can be very annoying, these bugs are vital to the ecosystems of Pigeon Lake! Feeding many of the other species we appreciate that live in the area!