Hover flies
Scientific Name
More than 25 species of flower flies have been identified in Ontario tender fruit orchards, including Allograpta spp., Platycheirus erraticus Curran, P. hypoboreus (Stalger), P. obscurus (Say), P. quadratus Say, Sphaerophoria contiqua Macquart, S. philanthus Meigen Syrphus ribessi (L.) and Toxomerus germinatus (Say) and T. marginatus (Say)
Identification
The Pentatomidae, or stink bugs, are large (1–2 cm) oval or elliptical-shaped insects that have a well developed scutellum or shield and an odoriferous gland, the secretion of which repels other predators. This gland is located on the 3rd thoracic segment in adults and dorsally in the 3rd–5th abdominal segments in nymphs.
Eggs:
- White eggs are deposited singly on leaves usually near aphid colonies
- Larvae are slug-like and pointed at one end
- Mottled brown and/or green colour patterns
- Reach sizes of 5-12 mm
- Inactive, tan or brown, and oblong or oval in shape
- Reach sizes of 5-10 mm
- Mature larvae pupate on stems and leaves or in the soil, and the pupal period lasts about 14 days
Adults:
- The adults of many species are dark brown with yellow bands, giving them a bee -like appearance
- Unlike wasps and bees, which have two pairs of wings, adult flies have a single pair of wings
- They have a habit of hovering in mid-air (hence the name)
Often Confused With
Aphid midges – syrphid fly larvae are generally larger and the internal organs are more readily observed.
Interaction With Host
Adult flower flies are important pollinators. They are not predaceous but feed on pollen, nectar and aphid honeydew. A female lays up to 400 eggs. Larvae are often found in aphid colonies feeding on aphids. They pierce the bodies of aphids and suck their fluids, leaving shriveled, blackened bodies. Each larva consumes more than 500 aphids, and may also feed on scales, mites and small caterpillars.
Period of Activity
Syrphids generally overwinter as mature larvae, but in some species adults also overwinter. Adults are most active in orchards from late June to late July. The larvae of many species are active at night, and can be observed feeding in aphid colonies. There are several generations per year.
Insects Attacked
Each larva consumes more than 500 aphids, and may also feed on scales, mites and caterpillars.
Monitoring and Management
Monitor for their presence in terminals when monitoring aphid populations. The presence of aphid midges and other aphid predators can delay or prevent the need for insecticide applications.
