University of Maryland Extension

Phorid Fly

phorid fly
Phorid flies on sticky tape
Photo: Whitney Cranshaw, Colorado State University,

  • Their common name, humpbacked fly, reflects their humpbacked appearance
  • Adults are about 1/64 - 1/4" in size. 
  • There are several species of small black flies that may occasionally become pests in buildings.
  • These can include phorid flies which breed in decaying organic matter of plant or animal origin. 
  • Extremely large numbers of phorid flies on the first floor of a structure may indicate a broken drain or sewer line under the structure.
  • Remove or dry the organic matter where the larvae live will eliminate the problem.



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