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Mydas Flies

Mydidae[3]

Mydas flies are large, harmless flies that mimic wasps; the eastern Mydas clavatus is black with an orange band on the abdomen.[1][2]

Group
Insect
Order
Diptera
Family
Mydidae
US records
40 states
Sources
3 cited
Updated
2026-10-16
Black Mydas fly with an orange band on its abdomen resting on a leaf
Black Mydas fly with an orange band on its abdomen resting on a leaf. (c) Kristof Zyskowski, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Related profiles
  9. Common questions
  10. Sources

How to identify it

  • Most are about 1 inch long, ranging from 1/4 to 1 1/4 inches; Clemson describes one at about 1 1/2 inches.[1][2]
  • Many are black, dark or tan with red, orange or yellow bands; Mydas clavatus has a golden or reddish mark on the second abdominal segment.[1]
  • Like all true flies they have one pair of wings, and unlike most flies they have clubbed antennae.[1]

Look-alikes

Look-alikeHow to tell them apart
Robber fliesA related group of large bee and wasp mimics, but robber flies lack clubbed antennae.[1]
Spider waspsMydas flies mimic blue-black spider wasps with an orange or red spot on the abdomen; wasps have four wings, flies two.[1]

Where it lives

About 80 species live in North America, with the most in dry areas such as the desert Southwest; Mydas clavatus and others occur in the East.[1][2]

US map: public records from 40 states since 1990 (GBIF).

Biology and life cycle

Larvae live in soil or rotting wood, and most species probably spend at least a year as larvae.[1]

Adults are short-lived and feed on flower nectar and pollen.[1][2]

Damage and signs

  • No damage; the larvae prey on beetle grubs, including root-eating lawn grubs, and have been proposed for biological control on sod farms.[1]

Health risk

Harmless; they do not sting or bite.[1]

Control

Prevention

No control is needed; these harmless flies are less common than other flies and feed on beetle grubs as larvae.[1]

Common questions

Is the big black wasp with an orange band a Mydas fly?
It may be; count the wings and check for clubbed antennae, since Mydas flies have two wings and wasps four.[1]
Do Mydas flies sting?
No; they are harmless wasp mimics.[1]

Sources

  1. Missouri Department of Conservation, “Mydas Flies (Field Guide).” mdc.mo.gov/discover-nature/field-guide/mydas-flies (accessed 2026-10-16)
  2. Clemson Cooperative Extension Home & Garden Information Center, “Meeting a Mydas Fly (HGIC, July 2024).” hgic.clemson.edu/meeting-a-mydas-fly/ (accessed 2026-10-16)
  3. iNaturalist, “Mydas clavatus taxon page (order and family).” www.inaturalist.org/taxa/123516 (accessed 2026-10-06)

Updated 2026-10-16. Built from sourced records. Spot an error? Tell us.