Hosts or Prey
All types of Sternorrhyncha (plant-sucking insects, formerly Homoptera) except whiteflies, most commonly adelgids, aphids, mealybugs, and scales
Identification
Adults are stocky flies with a body that is 1/25 to 1/8 inch (1–4 mm) long. The head is as wide or wider than the thorax with prominent eyes. Adults are called silver flies because many species are grayish to silver, commonly with a powderlike, whitish coating on the abdomen and thorax. Adults can have black or brown stripes on the thorax, dark spots or bands on the abdomen, or both. Some species are mostly brown or shiny black.
Eggs are oval and 1/50 inch (0.5 mm) or less in length. They are commonly whitish with longitudinal markings visible under magnification.
Larvae have distinct segments, a wrinkly surface, and a rounded rear end with 2, widely spaced breathing tubes (anal spiracles). Most species are 1/5 inch (5 mm) or less in length. Larvae commonly are yellow or whitish, but can be brown or greenish, covered with grayish wax, or the coloration of prey when body contents are visible through the skin.
Pupae occur in the hardened skin of the last instar (puparia), attached to plants near where they fed as larvae. Puparia are brown or orangish, 1/8 inch (4 mm) or less in length, and have two projections that were the rear-end breathing tubes.
Lookalikes
Larvae resemble those of predaceous midges and syrphids; all three types of predators can occur together where aphids are present. For species that feed openly on foliage, aphid flies are distinguished from midges and syrphids by the two, widely separated breathing tubes at the rear end and the presence of six to eight pairs of abdominal prolegs.
Life Cycle
Aphid flies develop through four life stages: egg, larva, pupa, and adult. After hatching, larvae develop through three, increasingly larger instars before pupating.
Aphid flies have one to several generations per year. Overwintering is as inactive, mature larvae (prepupae) or pupae in protected locations.
Habitat
Females lay eggs singly near colonies of prey for the larvae. Adults generally do not visit blossoms. They consume honeydew from plant surfaces or directly from prey of their larvae. Adults will stroke the upper surface of an aphid, causing it to excrete a droplet of honeydew. This aphid response evolved in association with tending by ants, which similarly milk aphids to receive a honeydew droplet in exchange for protecting aphids from parasites and predators.
Larvae are slow-moving and commonly ignored by ants tending aphids or other honeydew-producing insects. Larvae prey on adelgids, aphids, mealybugs, phylloxera, scales, and other types of Sternorrhyncha except whiteflies. Many species specialize on one type of prey, such as aphids or adelgids. Aphid flies are believed to be important biological control agents of pests, including certain species of adelgids, aphids, and phylloxera.
Species
Over 330 species of aphid flies have been described worldwide. Known in California in the genera Leucopina, Leucopis, and Pseudodinia, are 2, 8, and 2 species, respectively. Several additional species known in neighboring states may also be present here.
More Information
- Aphid fly, Leucopis bellula, UC Irvine
- Biology and Immature Stages of Leucopis pimcola and Chamaemyia polystigma (Diptera: Chamaemyiidae), Canadian Entomologist
- Chamaemyiid Predators of the Hemlock Woolly Adelgid from the Pacific Northwest, In Implementation and Status of Biological Control of the Hemlock Woolly Adelgid, USDA Forest Service
- Diptera, Chamaemyiidae (Ochthiphilidae) - Description & Statistics, UC Riverside
- Manual of Nearctic Diptera, Vol. 2, Chamaemyiidae, Agriculture Canada
- Natural Enemies Handbook, UC Integrated Pest Management Program
- Protecting Natural Enemies and Pollinators, UC Integrated Pest Management Program
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Diptera
- Family: Chamaemyiidae
