NC State Extension Publications

Background and Description

Syrphid fly (or "hover fly") adults are small yellow and black flies of varying appearance less than 1/2 inch (12.5mm) long. Many are bee mimics and are often mistaken for "sweat bees" because of their habit of hovering around a person's face and arms. Larvae are roughly the same length as adults and may be yellow, green, white, or brown. Eggs are white, faintly ridged, approximately 1/25 inch (1mm) long, and resemble tiny grains of rice.

Syrphid fly larva

Syrphid fly larva

Eddie McGriff, University of Georgia, Bugwood.org

Syrphid fly larva

Syrphid fly larva

Steve Schoof, NCSU

Syrphid fly larva

Syrphid fly larva

David Cappaert, Michigan State University, Bugwood.org

Syrphid fly eggs

Syrphid fly eggs

Charles Olsen, USDA APHIS PPQ, Bugwood.org

Syrphid fly egg (L) with green aphid (R)

Syrphid fly egg (L) with green aphid (R)

Whitney Cranshaw, Colorado State University, Bugwood.org

Syrphid fly

Syphid fly

Steve Schoof, NCSU

Syrphid fly adult (on goldenrod)

Syrphid fly

Steve Schoof, NCSU

Syrphid fly

Syrphid fly

Jon Yuschock, Bugwood.org

Syrphid fly

Syrphid fly

Susan Ellis, Bugwood.org

Syrphid fly

Syrphid fly

Jon Yuschock, Bugwood.org

Syrphid fly

Syrphid fly

Charles Ray, Auburn University, Bugwood.org

Syrphid fly

Syrphid fly

Phil Sloderbeck, Kansas State University, Bugwood.org

Life history

Some syrphid fly species overwinter as adults, though most overwinter as larvae in leaf litter. Adults emerge in early summer and feed on nectar and the honeydew from aphids. Females lay hundreds of eggs on leaves near soft-bodied insect prey, usually aphid colonies. Larvae are blind and have no legs, but easily locate prey by "casting" their front ends from side to side. After 7 to 10 days they will pupate, often after dropping to the ground. There are several generations per year.

Predation

Syrphid fly adults are not predators, feeding only on pollen, nectar, and aphid honeydew. Larvae, however, are highly effective predators of green apple and spirea aphids, with each larva capable of consuming hundreds of aphids during the course of its development. After locating prey, larvae pierce them and suck them dry. They are often more effective than other predatory insects in cooler weather.

Syrphid fly larva feeding on aphids

Syrphid fly larva feeding on aphids

David Cappaert, Michigan State University, Bugwood.org

Syrphid fly larva feeding on aphids

Syrphid fly larva feeding on aphids

Steve Schoof, NCSU

Author:

Extension Entomology Specialist (Fruits/Vegetables)
Entomology

Publication date: Feb. 23, 2015

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