Frit Fly
Oscinella frit (Linnaeus), Chloropidae, DIPTERA


Adult -- Several different species attack grasses. These tiny flies are black or yellow in coloration and 1.5 to 2.5 mm long. The wings are short, broadly rounded at the tip and they are devoid of closed cells except close to the base (anal cell and subcostal vein are both absent). They have small mouths and short antennae each with a stout, bare hair.

Egg -- The eggs are tiny and colored an off-white.

Larvae -- The tiny larvae are off-white, legless maggots.


Distribution -- There are several species of frit flies that attack turf grasses and most of these are found throughout the United States.

Host Plants -- All common lawn grasses are susceptible with bent grass being most preferred. Other plants that are more susceptible than the above are wheat, rye, timothy and corn. In some instances, pasture grasses are also a preferred host.

Damage -- This pest may cause damage to bent grass greens on golf courses and occasionally to turf grasses. The small larvae tunnel into and feed on the grass stems near the soil surface. Plants that are infested generally wilt and die. The presence of this pest may be detected if large numbers of small black flies are observed over the grass surface from mid- to late morning.

Life History -- The life history varies slightly between species but in general the female lays eggs on grass leaves or stems. The eggs hatch and the small larvae bore into the stems. After reaching the last larval instar, pupation takes place in the damaged stems or in the soil and then adults emerge. There are generally several generations a year. Winter is passed in the larval stage at the base of the damaged plants.


For specific chemical control recommendations, consult the state agricultural extension service recommendations.