Pest description and crop damage The adult is a small yellowish fly, about 8 mm long, with bright green eyes and smoky bands across the wings. The maggots are white, cylindrical, and tapered at the head. The maggots develop inside and feed in the berry, making them inedible. Infested fruit often drop prematurely, but others remain on the bush. Infested berries show a discolored area where the egg was inserted. Infested fruits often turn red before they drop.
Biology and life history The insect overwinters as a brown pupa about the size of a wheat grain in organic debris, or 1 to 3 inches deep in the soil at the base of the plant. In the middle of April, the flies emerge over a period of 40 to 45 days. The female flies insert oblong eggs under the fruit skin. The eggs hatch and the larvae burrow under the fruit skin, then into the fruit pulp. They feed on the pulp and seeds until mature, then burrow out through the skin and drop to the soil. There is one generation per year. Adult flies frequently rest on fence rows, brush, and trees adjacent to currant and gooseberry plantings.
Scouting and thresholds Scout fields in early spring for fly activity. Inspect fruit as they mature for any discoloration, and remove them from the plant.
Home gardeners: Use floating row covers to protect plants during adult emergence. Do not use this technique on infested plantings! Remove infested fruit when it appears. Lay a tarp under the plants to prevent flies from pupating in the soil.
Management-chemical control: HOME USE
There are currently no products labeled for home use.
Management-chemical control: COMMERCIAL USE
Apply chemical sprays when adults are present and active.
- bifenthrin (Brigade and other brands) at 0.033 to 0.1 lb ai/A. PHI 1 day. Toxic to bees; do not use when bees are foraging. Also toxic to fish and other aquatic invertebrates.
- carbaryl (Sevin and other brands) at 1.5 to 2.0 lb ai/A. PHI 7 days. Toxic to bees; do not use when bees are foraging. Latex-based formulations such as Sevin XLR Plus are less hazardous to bees. Also toxic to fish and other aquatic invertebrates. Do not exceed 10 lb ai/A per year.
- fenpropathrin (Danitol) at 0.2 to 0.3 lb ai/A. PHI 3 days. Do not exceed 0.6 lb ai/A per season. Toxic to bees; do not use when bees are foraging. Also toxic to fish and other aquatic invertebrates. Restricted use pesticide.
- pyrethrins (several brands)-Consult label for rate and use directions. PHI 0 days. Direct contact is essential for effective results. Toxic to bees; do not use when bees are foraging. Also toxic to fish and other aquatic invertebrates. Many brands, such as Pyganic, are OMRI-listed for organic use.
- spinosad (Entrust) at 0.062 to 0.1 lb ai/A. PHI 3 days. Entrust is OMRI-listed for organic use. Toxic to bees exposed to treatment for 3 hours following treatment. Do not use when bees are foraging. Also toxic to fish and other aquatic invertebrates. Do not apply when bees are foraging.
- zeta-cypermethrin (Mustang) at 0.05 lb ai/A. PHI 1 day. Toxic to bees; do not use when bees are foraging. Also toxic to fish and other aquatic invertebrates. Restricted use pesticide.