Rust flies

Definition

A family of small to medium-sized flies (Diptera: Psilidae) characterized by reduced wing venation, a humped thorax, and larvae that typically feed internally in plant stems or roots, often causing rust-colored damage or gall-like swellings in their hosts. Adults are slender with long legs and are commonly found in moist, vegetated habitats.

Etymology

From the rust-colored frass or damage symptoms associated with larval feeding in plant tissues, particularly in umbelliferous crops.

Example

The carrot rust fly (Psila rosae) is a major agricultural pest whose larvae tunnel into carrot roots, rendering them unmarketable and providing entry points for secondary pathogens.

Synonyms

• Psilidae

Related Terms

• Root maggots
• stem borers
• Diptera
• agricultural entomology
• plant galls
• umbellifers

Usage Notes

The common name 'rust flies' applies specifically to family Psilidae, not to flies that merely appear rusty in color. Larvae are often called 'rust fly maggots' in agricultural contexts. The family is sometimes confused with Agromyzidae (leaf-miner flies) or Anthomyiidae (root-maggot flies), but Psilidae are distinguished by their distinctive wing venation with a characteristic 'psilid gap' in the radial veins and their preference for Apiaceae and related plant families.