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An adult blueberry maggot
is a small, black fly, about 3/16 inch long. It can be recognized by a distinctive pattern of black bands running diagonally across each wing, white bars on each side of the thorax, a white spot at the posterior tip of the thorax and white lines along the back edge of each abdominal segment. Larvae develop entirely within the blueberry fruit and grow to about 1/2 inch in length. They have tapered, worm-like bodies with no legs, eyes or antennae. Facts:
- Have been found throughout the eastern United States including Alabama, Connecticut, Delaware, Florida, Georgia, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, Tennessee, Virginia and West Virginia.
- Overwinter as pupae buried 1 inch to 6 inches deep.
- Warm temperatures in the spring trigger pupal development.
- Adult flies usually begin emerging shortly after highbush blueberries start to ripen.
- After a seven-to-10-day pre-oviposition period, female flies begin to lay eggs on large, ripening berries.
- Larvae hatch in about five days, burrow into the berry and feed on the pulp for about two weeks.
- Mature larvae drop out of the berry and burrow into the soil to pupate.
- There is only one generation per year, but a few pupae may remain in the soil for two or three years.
- Berries become soft, mushy and unmarketable from maggots feeding within the berries.
- Infestations of blueberry maggot can be detected before they reach damaging levels by trapping the adult flies on yellow sticky boards (2-4 traps per acre) baited with ammonium acetate or protein hydrolysates.
- Sites where large bushes shade the ground through most of the day seem to provide optimal habitat for maggot survival. A statistical model can be used to estimate infestation probabilities for different sites based on bush height and row spacing. The model has proven to be quite reliable for non-irrigated fields in southeastern North Carolina.
- A short-residual pesticide should be used as a foliar spray to protect the fruit. Apply this spray from the ground whenever possible to get maximum coverage on the lower half of the bushes. Use an ultra-low-volume (ULV) spray by air only when weather, labor or harvest conditions make ground sprays impractical.
- Tank mixing an insecticide with a bait formulation containing protein hydrolysates can improve efficacy by making the spray residue more attractive to newly emerged adults.
- Spot infestations can be eradicated if they are sprayed every seven to 10 days until no fruit remains on the bushes.
- Some beneficial insects may be used for control. At least two species of parasitic wasps in the family Braconidae attack the blueberry maggot in the eastern United States, sometimes causing up to 40 percent mortality.
- Ants also provide natural control by their predation on larvae and pupae in the soil.
- Contact your local Cooperative Extension Service office for control measures recommended for your area.
- Blueberry Maggot. North Carolina State University Cooperative Extension Service. Retrieved 06 July 2010.
- Blueberry Maggot. University of Florida Entomology Department. Retrieved 09 June 2011.
- Boller, E. F., and R. J. Prokopy. 1976. Bionomics and management of Rhagoletis. Ann. Rev. Entomol. 21: 223-246.
- Howitt, A. J., and L. J. Conner. 1964. The response of Rhagoletis pomonella (Walsh) adults and other insects to trap boards baited with protein hydrolysate baits. Proc. Entom. Soc. Ont. 95: 134-136.
- Lathrop, F. H., and C. B. Nickels. 1932. The biology and control of the blueberry maggot in Washington County, ME. USDA Tech. Bull. 275.
- Longstroth, Mark. Blueberry Maggot. Michigan State University Cooperative Extension Service, Bulletin 861. 07 October 2009. Retrieved 14 July 2010.
- Nielson, W. T. A. 1984. Capture of blueberry maggot (Rhagoletis mendax) adults on Pherocon AM traps and on tartar red sticky spheres in low bush blueberry fields. Can. Entomol. 116: 113-118.
- Tomlinson, W. E. 1951. Influence of temperature on emergence of the blueberry maggot. J. Econ. Entomol. 44: 266-267.