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Australian Sod Fly

Inopus rubriceps[3]

The Australian sod fly (Inopus rubriceps) is a soldier fly whose larvae feed on the roots of grasses. In California it turns up only occasionally, and only in the San Francisco Bay Area, where it thins turf that weeds then fill in. In Australia its root-feeding larvae attack sugarcane.[1][2]

Group
Insect
Order
Diptera
Family
Stratiomyidae
US records
1 state
Sources
3 cited
Updated
2026-11-09
Female Australian sod fly, a black fly with a red head, on a leaf
Female Australian sod fly, a black fly with a red head, on a leaf. (c) wild_wind, 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

  • Adult males are black with yellowish legs and about 1/4 inch (6 millimeters) long. Females are larger, about 0.4 inch (9.5 millimeters), black with reddish legs and a red head.[1]
  • Full-grown larvae are legless maggots about 1/2 inch (1.3 centimeters) long with a flattened, distinctly segmented, light tan body with a coarsely granular surface, six long stiff bristles on each segment and a distinct, cone-shaped black head.[1]

Look-alikes

Look-alikeHow to tell them apart
March fly larvaeMarch fly maggots also live in turf but mostly feed on decaying organic matter. Sod fly larvae are told apart by their flattened, distinctly segmented bodies.[1]

Where it lives

In California it is found only occasionally, and only in the San Francisco Bay Area. In Queensland, Australia, sugarcane researchers have studied the damage its root-feeding larvae do to cane.[1][2]

US map: public records from 1 state since 1990 (GBIF).

Biology and life cycle

Adults may fly in May, but their main period of activity is September through November.[1]

Eggs are laid in the soil, and after hatching the larvae may take two years to complete development.[1]

All turfgrass species are susceptible. In sugarcane trials the larvae fed on roots, slowing shoot growth and sharply reducing the regrowth (ratoon) shoots after harvest.[1][2]

Damage and signs

  • Larvae feed on sap from grass roots. The grass gradually declines and is replaced over time by broadleaf weeds.[1]

Health risk

UC IPM treats it only as a turf pest and describes no harm to people.[1]

Control

Prevention

Keep turf well maintained, adequately watered and vigorously growing; such a lawn can normally withstand a moderate sod fly infestation.[1]

Pesticides

No insecticides are registered for it, and there are no known biological or cultural controls.[1]

Common questions

What are the flat, bristly maggots in my Bay Area lawn?
They could be Australian sod fly larvae: legless, flattened, light tan maggots about 1/2 inch long with stiff bristles on each segment and a black, cone-shaped head. They feed on grass roots.[1]
How do I control Australian sod fly?
There are no registered insecticides or known biological controls. The best defense is healthy, well-watered turf, which can tolerate a moderate infestation.[1]

Sources

  1. University of California Statewide IPM Program, “Australian Sod Fly (Pest Management Guidelines: Turfgrass).” ipm.ucanr.edu/agriculture/turfgrass/australian-sod-fly (accessed 2026-11-09)
  2. Journal of Economic Entomology (via NCBI PubMed), “Effect of feeding by larvae of Inopus rubriceps on development and growth of sugarcane (P. R. Samson; Journal of Economic Entomology 94(5), 2001; abstract).” pubmed.ncbi.nlm.nih.gov/11681671/ (accessed 2026-11-09)
  3. iNaturalist, “Inopus rubriceps taxon page (order and family).” www.inaturalist.org/taxa/357883 (accessed 2026-11-09)

Updated 2026-11-09. Built from sourced records. Spot an error? Tell us.