Midges and Gnats

Midges and gnats are common names for many different tiny two-winged flies (Diptera) that congregate over birdbaths and soggy areas.

Gall midge (Alvesgaspar) CC BY-SA 3.0

Midges and gnats are found everywhere there is moisture, including the Arctic and Antarctica. Some of them bite, and some of them don’t. The words are used interchangeably, depending on where you live and who you ask.


We have already discussed fungus gnats, but the midge family is huge. To be accurate, most gnats are biting insects in the Nematocera suborder (making them distant cousins to mosquitoes). Midges can be from non-biting, phantom, or biting families. You can see why it gets confusing.


Midge/gnat life cycle

You may have seen swarms of tiny insects over a birdbath or wet soil some summer evenings. These swarms are mating dances that may last for several days. Some of these swarms can get big enough to hear, and they may look like clouds of smoke from a distance. In some cases, roads can become so slick with gnats that accidents occur. These insects may also sun themselves on the side of a house in such numbers that it appears coated.


Many midge adults do not have mouths. They only live long enough to reproduce. After mating, masses of 3,000 to 10,000 eggs are laid on water or wet soil, and the adults die a couple of days later. The eggs sink to the ground and hatch in 2 or 3 days. Larvae look like microscopic grubs and can be green, red, or white. Most midge or gnat larvae spend this stage in water or burrowed into mud. There can be up to 4,000 larvae in a square foot of mud. These larvae feed on algae and other organic matter. At this stage, they are helpers in the decomposition process. After 4 weeks or so, the larvae begin to pupate. Two days later, they emerge as adults, and the cycle continues.

Gall midge pupa in goldenrod stem (Polinizador) CC BY-SA 4.0

Biting midges

Biting midges (D. Ceratopogonidae) are blood-suckers. Like mosquitoes, these midges need blood to reproduce. This group includes black flies, no-see-ums, and sand flies, which inflict painful bites and can transmit human diseases. Some members of this group also suck the bodily fluids from insects. Many of them also drink nectar. Larval biting midges are sometimes called bloodworms because they contain blood.

A midge sucks the bodily fluids from the knee of a mantis as it eats a bee (JonRichfield) CC BY-SA 3.0

Phantom midges

Phantom midges (D. Chaoboridae) are also known as glassworms. You can see why

Phantom midge larva (Piet Spaans) CC BY-SA 2.5

Most phantom midge adults do not eat. Those that do only drink nectar. Phantom midge larvae are rather bizarre in that their antenna have evolved into grasping organs that crush prey and other foods, somewhat similar to the hands of a mantis.

Male phantom midge (Richard Bartz) CC BY-SA 2.5

Nonbiting midges

Several midges create galls and damage buds, leaves, or roots. Some of the more common midges, and the plants they damage, include:

• Barley midge, or Hessian fly (Mayetiola destructor)--barley, rye, wheat
• Brassica pod midge (Dasineura brassicae)—all members of the cabbage family
• Lentil flower midge (Contarinia lentis)--lentils and other legumes
• Millet grain midge (Geromyia penniseti)--millet and other cereals
• Pear midge (C. pyrivora)--apples and pears
• Raspberry cane midge (Resseliella theobaldi)--cane fruits
• Rosette gall midge (Rhopalomyia)--citrus (Porricondylini spp.); garlic, ginger, onions, potatoes, and sweet potatoes (Lestremia spp.)
• Sorghum midge (C. sorghocila)—millet, sorghum
• Soybean pod gall midge (Asphondylia yushimai)--soybeans and other legumes
• Swede midge (C. nasturtii)--parsnips, radishes, turnips
• Wheat blossom midge (Sitodiplosis mosellana)--wheat

When midges damage plants, the first signs will be small discolored areas, general failure to thrive, and wilting. Over time, the effects of midge feeding and burrowing can significantly reduce crop size. It also makes plants susceptible to other pests and diseases.


Midge management

Removing standing water is always a good idea, and not just because of midges. Mosquitoes can be more than just a summer annoyance. These tips can help manage both midges and mosquitoes:

• Keep rain gutters clear of debris.
• Eliminate any standing water in planter pots, yard art, unused buckets, and other containers.
• Dump out and replace outdoor pet water every day or two.
• Increase drainage in soggy soil with aeration or furrows, or turn it into a rain garden.
• Add Bacillus thuringiensis (Bt), also known as mosquito dunks, to rain barrels, pet water, and birdbaths.

Interesting fact: chalcid wasps (the ones who give us figs) are midge and gnat predators.


If midges have become patio pests, turn off your lights or get one of those bulbs that claim to not attract insects. [I’m not sure how well they work. Have you had any experience with them? I’d love to hear about it in the comments.]


Beneficial midges

Some midges are major pollinators of the cocoa tree, so they aren’t all bad. There are also predatory midges. Aphid midges (Aphidoletes aphidimyza) devour aphids, while predaceous gall midges (Feltiella acarisuga) protect your plants against a surprising number of spider mites.


May all your midges be beneficial, and gnats be absent from your landscape.