NC State Extension Publications

General Information

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March flies range from fragile to sturdy insects with relatively short antennae and dark bodies. Some species are marked with red or yellow spots. March flies are 14 to 12 inch long. March fly larvae are gray, leathery maggots with well defined heads. The body has numerous small bumps and protrusions. March fly maggots are 14 to 1 inch long.

Female March flies have smaller eyes.

Female March flies have smaller eyes.

March flies

March flies tend to be dark gray although some have bright spots of color.

March fly maggots have projections

March fly maggots have projections at the rear.

March fly maggots

March fly maggots are gray and usually found in damp soil.

March fly pupae

March fly pupae are slender and unattractive.

Biology

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March flies are found throughout North America, but large flights of March flies occur primarily in the southeastern United States. March fly maggots develop in decaying organic matter. Adults visit flowers presumably for nectar. The principal concern over March flies arises with the sudden appearance of swarms of these flies over ornamental and fruit crops and around homes. When their swarms cross roads and highways, large numbers splatter on trucks and automobiles. Visibility may be reduced, and when the flies are especially abundant, vehicles may overheat because the flies clog radiator fins. If left on car finishes too long, the fatty tissue of the flies and their eggs may pit or mar the paint.

After mating, female March flies enter the soil where they lay 200 to 300 eggs. The maggots hatch from the eggs and feed on leaf litter and sometimes among the roots of living plants. They have been reported from potatoes which had been previously damaged by wireworms. Their feeding hastens the breakdown of plant tissue into humus. March fly adults often emerge in early to late spring. (Sometimes there is a fall flight also.) These flies visit flowers and are sometimes effective pollinators.

March flies often wind up splattered on the front of cars.

March flies often wind up splattered on the front of cars.

Control

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March flies are a nuisance, but they do not represent any threat to the health of plants, animals or humans. The principal concern over March flies arises with the sudden appearance of swarms of these flies over ornamental and fruit crops and around homes. When their swarms cross roads and highways, large numbers splatter on trucks and automobiles. Visibility may be reduced, and when the flies are especially abundant, vehicles may overheat because the flies clog radiator fins. If left on car finishes too long, the fatty tissue of the flies and their un-laid eggs may pit or mar the paint. A large scale control of immature or adult March flies by chemical means would place an undue pesticide load on the environment. The most troublesome species of March flies swarm during warm daylight hours, so driving at night might avoid the problem for travelers. A screen across the front of the radiator will protect the radiator from clogging. Temporarily smearing the front of the car with baby oil or spraying it with a no-stick cooking product will aid in the removal of splattered flies later.

Other Resources

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For assistance with a specific problem, contact your local Cooperative Extension Center.

Authors

Professor and Extension Specialist
Entomology & Plant Pathology
Professor Emeritus
Entomology & Plant Pathology
Retired Extension Specialist (Home Ornamentals/Turf)
Entomology & Plant Pathology

Publication date: May 1, 1997
Revised: Oct. 3, 2019

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