Insect Identification logo

Flower Fly (Toxomerus marginatus)

Detailing the identifying qualities of the Flower Fly, including physical features and territorial reach.

 Updated: 8/4/2017; Authored By Staff Writer; Content ¬©

  Flower Fly  
Picture of Flower-Fly-Toxomerus-Marginatus

Flower Flies in the Toxomerus genus look like wasps, giving them a bit of peace while they scour plants for aphids and other plant pests.

Seeing this Flower Fly in the garden is a win. Not only is it harmless to people, it helps clear vegetable and fruit plants of insects that drain and damage them. They are keen mimics of wasps with similar colors and banding on the abdomen, but a look at the eyes and antennae reveal what they really are. In this species, female eyes are separated (see photo), while male eyes are smashed right next to each other (holoptic).

Active from spring through autumn, females lay fertilized eggs on plants and the larvae feed on aphids, small caterpillars and other soft-bodied insects they encounter. Larvae look like green worms with a yellowish coloring down the middle and a thin dark line along the 'back'. They are well camouflaged for the green foliage they live on. So efficient and hungry are these larvae that they may completely eliminate a population of aphids off of a plant by harvest time. Adults drink nectar and may be seen visiting flowers.

References: University of California-Davis Department of Agriculture and Natural Resources (publication #8285); Field Guide to Insects of North America by Kaufman

Flower Fly Information

Category: Fly or Mosquito
Common Name: Flower Fly
Scientific Name: Toxomerus marginatus

Taxonomy Hierarchy

 Arrow graphic Kingdom: Animalia
  Arrow graphic Phylum: Arthropoda
   Arrow graphic Class: Insecta
    Arrow graphic Order: Diptera
     Arrow graphic Family: Syrphidae
      Arrow graphic Genus: Toxomerus
       Arrow graphic Species: marginatus

Size, Identifying Tags and Territorial Reach

Size (Adult, Length): Size (Adult, Length): 5 mm to 6 mm (0.195 inches to 0.234 inches)
Identifying Colors: yellow, black, orange
Additional Descriptors: metallic, stripe, band, diamond, wasp, bee, flying, helpful

North American Territorial Reach (Though Not Limited To): Alabama; Alaska; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Hawaii; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming; Alberta; British Columbia; Manitoba; New Brunswick; Newfoundland and Labrador; Nova Scotia; Ontario; Prince Edward Island; Quebec; Saskatchewan; Mexico

A Note About Territorial Reach: Keep in mind that an insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above. Insects are driven by environmental factors, food supplies and mating patterns and do not nescessarily work within hard-and-fast territorial lines like we humans do.

BugFinder: What is it?