Southeastern Apple Production
ENTOMOLOGY
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Southeastern Apple ProductionENTOMOLOGY |
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The apple maggot (AM) adult is a small fly slightly smaller than a housefly. The body is black with white bands between segments on the abdomen - females have four bands, males have three. The clear wings are conspicuously marked with four oblique black bands. The larval stage is a 1/4-inch long, white, legless maggot that is difficult to detect inside the fruit. The pupa is brown and oblong.
 Adult |
 Larvae |
 Pupae |
Historically, AM has been a sporadic pest of apples in the southeastern US, but when it does occur it can cause considerable damage. AM usually completes one generation per season, but two generations are known to occur in some years. Adult flies emerge from overwintering pupae in the soil from June through September, with the major emergence period being from mid July to early August. About 7 days after emergence, flies become sexually mature and mate, after which females deposit eggs under the skin of apples by puncturing apples with their ovipositor. After a few days a small maggot hatches from the egg, and the maggot tunnels into the fruit. When mature, the maggot exits the apple, drops to the ground, and burrows into the soil, where it completes development and forms a pupa. The pupa is the overwintering stage, and it emerges as a fly the following summer. Although the majority of overwintering pupae emerge the following spring, some pupae do not emerge for 2 to 4 years. Weather conditions are important in dictating the timing and length of fly emergence.
Pupae overwintering in lighter soils and in sunny areas emerge before those in heavier soils and shady areas. Sufficient soil moisture is also necessary for flies to emerge from soil-borne pupae; drought delays or prevents many flies from emerging. Abandoned orchards (or even a few nonsprayed trees) and wild hawthorn trees are potential sources of large numbers of flies and are a threat to commercial orchards located within at least 400 yards.
AM larvae are sometimes called "railroad worms" because they leave brown winding trails just under the apple skin of some varieties. A decay organism associated with the burrowing maggot sometimes reduces apples to a brown rotten mass. Apples may also be pitted and dimpled with numerous tiny egg punctures.
 Interior damage |
 Exterior "dimpling" damage |
Monitor AM adults with red sticky spheres alone or in combination with a volatile bait. Baited spheres catch two to four times as many adults as nonbaited spheres. In orchards with no history of maggot injury, a minimum of three red spheres should be placed on the outside row of an orchard closest to the suspected source of flies (e.g., abandoned orchard). Hang spheres in trees with fruit, but remove fruit adjacent to the sphere so that the sphere is clearly visible. Apply an insecticide within 7 to 10 days after catching the first fly, and repeat applications at 10- to 14-day intervals while adults are active.
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| AM sphere trap with bait essence |
Insect and Mite Management Overview
Insect and Mite Index
Southeastern Apple Production
Mountain
Horticultural Crops Research & Extension
Center
455 Research Drive
Mills River, NC 28759
Phone: 828.684.3562 ~ Fax: 828.684.8715
Email: jim_walgenbach@ncsu.edu
Web Crafters: Anne S. Napier and
Steve Schoof
Email:
steve_schoof@ncsu.edu
Updated March 26, 2007