How to Manage Pests
UC Pest Management Guidelines
Scientific Name: Oscinella frit
(Reviewed 9/09, updated 9/09, pesticides updated 12/16)
In this Guideline:
DESCRIPTION OF THE PEST
Adult frit flies are slightly more than 0.062 inch long, shining black with small yellow markings on the legs. The eggs are pure white, 0.03 inch long, with a finely ridged surface. Mature larvae are 0.125-inch long, yellow, with black, curved mouth hooks. Pupae are yellow at first, then turn dark brown and are slightly less than 0.125 inch long.
The winter is passed in the larval stage in the stems of grasses. Pupation takes place in spring, and the first adults emerge about March. Eggs are laid on the leaves and leaf sheaths of grasses. Several larvae may occur in one plant. There are at least three broods, the activity of the last extending into October in warmer areas.
All species of turfgrass are susceptible, but bentgrasses and bluegrasses seem to be the most susceptible to injury.
Larvae tunnel in the stems near the surface of the soil, causing the upper portion of the plant to turn brown and die. Damage is most common on golf greens. Injury appears first on the collars of the greens and moves in toward the center. The high, or upper, sections are usually the first to show the symptoms. Greens with high organic matter content appear to be most susceptible.
Look for small, black adult flies hovering close to the grass from mid to late morning. Look for the larvae in the stems near the ground level. A hand lens or dissecting microscope is useful in finding the very small larvae. Treatments are rarely needed unless damage is occurring.
UC IPM Pest Management Guidelines:
Insects and Mites
A. M. Sutherland, UC Statewide IPM Program, Alameda County
Acknowledgment for contributions to Insect and Mites:H. K. Kaya, Nematology, UC Davis
J. Hartin, UC Cooperative Extension, San Bernardino County
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
K. Kido, Entomology, UC Riverside
H. S. Costa, Entomology, UC Riverside
D. D. Giraud, UC Cooperative Extension, Humboldt/Del Norte counties