Common Name: Flower Fly, Hover Bee, Hover Fly, Sweat Bee, Sweat Fly, Syrphid Fly
Scientific Name: Order Diptera, family Syrphidae
Size: Adult--less than 1/2", larva--1/8" to 1/4"
Identification: Adults look like bees or small wasps and are usually seen hovering around flowers. Males have a distinctive hovering and darting habit and shorter antennae than wasps. Some are very small, others are larger than house flies. They commonly raise and lower their abdomen when resting. They have two wings whereas bees and wasps have four. Wings are held out to the side at rest; bees fold theirs in. Hover flies don't bite or sting.
Biology and Life Cycle: Larvae are maggots that are usually whitish, but one species is green with a red or white stripe down the back. Maggots are tapered toward the head and usually found near aphids. The female lays tiny single eggs near aphids, and larvae hatch in two to three days. Small cylindrical legless maggots become sluglike and later turn into pear-shaped pupae attached to leaves or stems. Some drop to the ground to pupate in the soil. Adults emerge after two or three weeks. The life cycle (from egg to adult) takes two to six weeks. From one to seven generations a year. Overwinter as larvae or pupae. Complete metamorphosis.
Habitat: Vegetable crops attacked by aphids, especially cole crops and sweet corn. Also plants in herbal and ornamental gardens. Hover flies love flowers.
Feeding Habits: Adults are attracted to and feed on the nectar and pollen of many flowers. Larvae are predators on aphids, caterpillars, mealybugs, scale, thrips, corn borers, and corn earworms. They especially like small flat flowers such as carrots, Queen Anne's lace, horseradish, and wild mustard. They can often be seen on roses. The grublike green larvae love aphids. They hold them up and suck their juices as if drinking soda from a bottle and then toss the dry skin aside. They eat about one aphid per minute.
Economic Importance: Larvae are effective predators of aphids and other troublesome insects. Adults are important pollinators. The hover fly hurriedly floats from flower to flower, drinking nectar. By doing so, they are excellent pollinators, which we now need since so many of our honey bees are being destroyed.
Natural Control: None needed.
Organic Control: None needed.
Insight: Not commercially available yet. Hover flies can remain absolutely motionless in air where bees and wasps bob up and down. When syrphid flies land on flowers, their wings stop moving, but the buzz keeps buzzing. Attract these insect friends with plants that produce lots of pollen and nectar--such as sweet alyssum, buckwheat, caraway, chickweed, dill, fennel, wild lettuce, morning glory, silver lacevine, yarrow, and other plants in the daisy and carrot families. Coreopsis, coriander, sunflowers, scabiosa, blue-eyed grass also help to attract hover flies.