One common fly in Florida is often mistaken for a harmful fruit fly and that is the Allograpta obliqua (Say), a hover fly, flower fly, or syrphid fly.  Their ability to hover and fly backwards is unique and therefore, the name hover fly.  As adults they are considered to be important for the cross pollination of some plants. The larvae are beneficial predators that feed on aphids, a common pest for strawberry growers.

Common Name:  Hover fly, flower fly, or syrphid fly

Scientific Name:  Allograpta obliqua (Say)

Description:  The egg is creamy white, microscopically sculptured, elongate oval, about .84 mm in length and .25 mm in diameter. The full-grown larva is 8 to 9 mm in length, 2 mm wide, and about 1.2 mm in height; elongate oval, somewhat flattened on dorsum, the anterior end drawn out to a point when the insect extends itself; integument finely papillose, transversely wrinkled. The fleshy conical elevations are surmounted with pale spines, colored green, with two narrow whitish longitudinal stripes flanking the dorsal vessel. Posterior respiratory tubes fused mesad .5 mm long, the combined base about 27 mm wide.  The puparium is green; the two whitish larval stripes apparent for a day or two. As the true pupa inside takes on the black and yellow color of the adult, the color of the puparium changes until all of the green disappears. The puparium length averages 5.25 mm, width 2.5 mm and height 2.3 mm. Posterior elevation is very gradual. The adult is 6 to 7 mm long. This species may be recognized by the generic characters -- yellow thoracic stripes and abdominal crossbands; on the fourth and fifth segments, four longitudinal, oblique, yellow stripes or spots; and yellow face lacking a complete median stripe. 

Larval syrphid (hover) fly that feeds on aphids and other small arthropods.