The AM overwinters in the pupal stage in soil. As soil temperatures rise in early spring, development of pupae commences. The adult fly first emergence begins shortly thereafter (early summer, mid to late July this year in upper Illinois). It takes about 7 to 10 days for the female to mature enough to mate and lay eggs.  So there is a 7 - 10 day window for spraying prior to egg laying.  A feeding and mating period (pre-oviposition) during this 7-10 days is followed by egg laying directly under the skin of the apple. Females may deposit eggs over an approximate 30 day period laying as many as 300-500 eggs.  

Most commercial apple orchards have no indigenous populations of AM. AM infestations in commercial orchards result from flies immigrating into the orchards from outside sources. AM volatile-baited sticky spheres should be deployed along the edges of commercial orchards that are closest to outside sources of apple maggots (abandoned orchards, unsprayed homeowner’s trees, feral apple trees). Check traps at least once/week.

Egg-laying punctures cause dimples and distortion in the outer flesh of fruits. These punctures appear as pinpricks on the fruit surface. Larvae tunnel throughout the fruit leaving irregular trails.(Fig. 2)

As eggs hatch, larvae funnel through fruit flesh leaving a winding brown trail.(Fig. 3)  Egg laying usually ceases in early to late August; however, it may continue longer if drought conditions exist throughout August.

When monitoring for AM, the apple maggot fly tends to show a preference for golden delicious varieties, but no variety is immune from attack.  Sticky red spheres are effective monitoring devices for adult AM flies (Fig. 4). Females are attracted to the sphere for mating and egg laying activities and are trapped by the sticky coating. Hang traps shortly before expected adult emergence (early july in upper Illinois). First emergence may be detected by checking traps daily until the first fly is spotted on the non-baited trap. 

Hang the sphere in the proximity to fruit at eye level on the perimeter of the south or southeast side of the tree. Attach the ball in a sturdy stem about 1 foot above a fruit cluster of approximately 6-10, cleaning out the foliage and other fruit for at least 18 inches to sides and top of the trap so it is easily visible. The spheres attract the insects that come within a few yards of them; therefore, the capture of ONE AM on any one non-baited trap at a time would indicate the need for an immediate control application. The capture of 5 flies on a baited trap would  indicate the need for an immediate control application. Once the pesticide is applied, AM captures are disregarded for the period during which the protective spray is effective (varies according to pesticide used).  Trap kits are available at Gardens Alive by folowing this link, Gardens Alive.

Several insecticides can be used for apple maggot control including those used for codling moth control like acetamiprid or spinosad.  Acetamiprid is a soft, conventional control and may still be available as  Ortho Flower, Fruit & Vegetable Insect Killer .  Ortho has phased this product out of production, but there are still some bottles available on eBay.  This is a concentrate product that contains .05% acetamiprid, a synthetic organic compound of the family of chemicals that acts as  translaminar insecticides. These penetrate leaf tissue and remain there for the insect to digest, but do not travekl any further than the leaf and wash off in about 14 days.  Acetamiprid is a contact insecticide for sucking-type insects and can be applied as a foliar spray.  It acts on a broad spectrum of insects, including aphids, thrips, plum curculio, apple maggot and Lepidoptera, especially codling moth.  When sprayed in the evening at sunset, it will not harm bees or other beneficial insects.  Be sure to follow all label directions on the bottle for proper application.

An all natural approach is available in the form of Bonide’s Captain Jack’s Dead Bug Brew.  Captain Jack's Deadbug Brew® contains Spinosad (spin-OH-sid), a product first isolated from a naturally occurring soil dwelling bacterium that was collected on a Caribbean island from an abandoned rum distillery. Deadbug Brew® kills bagworms, borers, beetles, caterpillars, codling moth, gypsy moth, loopers, leaf miners, spider mites, tent caterpillars, thrips and more! Use on fruits, vegetables, berries, citrus, grapes, nuts and ornamentals and approved for organic gardening.