Midge flies are undeniably irritating. The presence of non-biting midges may cause water and air filtration blockage and contamination. On the other hand, biting midges may cause painful, itchy bites that can lead to allergies and scarring.
Before a midge becomes fully-grown, it exists as a larva (the state in which it spends most of its life). Learning more about midge fly larvae may be crucial in eliminating, preventing, or avoiding them entirely.
Midge Life Cycle
Biting (Ceratopogonidae) and non-biting midges (Chironomidae) undergo complete metamorphosis (holometabolous) into adulthood. This means that after hatching from eggs, the larval and pupal stages are integral parts of their growth.
Two to ten days after they are laid, midge eggs hatch into larvae, which then burrow into the surface they are laid. This larval phase is the longest in the midges’ developmental cycle, lasting anywhere from 14 days to as long as 9 months.
Interestingly, their adult lives are short, in comparison to their larval stage, as mature midges may last between a day to 2-7 weeks.
Midge Fly Larvae
Development of midge fly larvae happen through four stages known as ‘instars.’ Only the first instar is planktonic, with the succeeding stages taking caterpillar, or worm-like body forms.
Both biting and non-biting midge fly larvae exhibit sclerotized (or hardened) head capsules attached to tubular, segmented bodies. In some groups, fleshy stumps or prolegs are developed for locomotion, but in most, only false-legs or pseudo-legs are observed.
Midge flies live out most of their larval lives at only 1-3mm long.
Biting Versus Non-Biting Midge Fly Larvae
As larvae, it can be difficult to distinguish between biting and non-biting midges, but there are significant differences. Perhaps most glaring is that non-biting midge larvae are often red due to the presence of hemoglobin in their hemolymphs, earning them the common name “bloodworms.”
Biting midge larvae, on the other hand, are commonly a creamy white color. Also, only ‘no-see-ums’ (biting midge) larvae have two strongly developed, divergent arms, between which are prominent combs for a pharyngeal apparatus.
Feeding Habits of Midge Fly Larvae
All midge fly larvae exhibit opportunistic omnivorous and detritivorous behavior. Decaying vegetable matter, algae, fungi, and other readily available nutrient-rich organic material serve as their plant-based sources of nourishment.
In addition, biting midge fly larvae are predators, getting sustenance from small insects (including the larvae of these) and nematodes.
As midge fly larvae are a primary food source for birds and other animals, they tend to feed deeper into the substrate during the day to evade their predators. Still, they remain close to the surface, with research showing that more than 50% of an observed larvae population can be found in only the top two centimeters of the substrate.
At night, with less probability of being hunted by birds, midge fly larvae may migrate to the mud or soil surface to feed.
Habitats of Midge Fly Larvae
Midge fly larvae require moisture and an abundance of organic matter to thrive. As a result, their habitats are distinctly aquatic or semi-aquatic.
Biting Midge Fly Larvae
Aquatic habitats include both saltwater and freshwater bodies of water. The shallow banks of lakes, swamps, and marshes are common hotbeds for biting midge larvae, as they obviously provide the needed water, as well as nutrient-dense mud and detritus.
More temporary water pools such as collected rainwater or wastewater seepage can also support biting midge larvae under the right conditions.
Common semi-aquatic habitats include wet woody debris such as rotting tree stumps, decaying plant waste such as damp fallen leaves, and even animal manure. These all make ideal breeding grounds for biting midge larvae by providing the nutrients needed for their growth and development.
Non-biting Midge Fly Larvae
In addition to the habitats above, non-biting midge larvae are specifically known to flourish in highly polluted bodies of water. This is due to commercial fertilizer waste boosting the water’s nutrient content.
Also, because of the hemoglobin in their systems, non-biting midge fly larvae can survive even in low-oxygen conditions such as man-made ponds and specialized habitats such as the insides of pitcher plants.
Eliminating Midge Fly Larvae
Many options for exterminating midges require dealing with midge fly larvae. Each method, however, has its pros and cons.
Larvicides are chemical insecticides formulated specifically for larvae. These may come in the form of liquids or soluble formats such as granules, which are usually added to the body of water believed to be a midge habitat.
However, as these substances also kill or harm other organisms in the same ecosystem, their environmental impact is largely thought to outweigh the benefits. Numerous advisories and guidelines seek to regulate the use of these pesticides.
Hence, in recent years, there has been increased interest in larvicides that use natural compounds. While more research on and further development of these eco-friendly options are required, they may be the next frontier in eradicating midge fly larvae.
Another method of eliminating midge fly larvae goes straight to the “source,” rendering habitats unlivable to deplete these insects’ population in an area. This essentially means stripping away the conditions needed for midge fly larvae to thrive: the presence of water and organic matter.
On a smaller scale that is actionable for most, this may simply mean ensuring proper disposal of natural waste such as fallen leaves and branches, getting rid of puddles and other standing water, or cleaning out gutters after rain showers. These are all simple, effective ways to help eliminate midge fly larvae.
However, applying this to a larger scale, it would mean draining entire bodies of water or landfilling. Not only are massive operations such as these are costly and time-consuming, but they also have a grave ecological and environmental impact, making them an impractical, unsustainable solution.