July 1, 2015

Apple Maggot has Arrived!

Fig. 1
On June 30, I trapped the first apple maggots of the season.  It only takes one trapped fly to  determine that they have arrived to the orchard!  The apple maggot (AM) is native to the Midwestern US and is considered a primary pest, along with plum curculio (PC), and codling moth (CM). The adult resembles a small housefly in size, with a black body, eyes of dark red, with the thorax and abdomen having distinctive white or cream colored bands. The AM is distinguished from other similar, and closely related flies by the dark banding on its wings (See Fig. 1).  

Fig. 2
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 June in upper Illinois). A feeding and mating period (pre-oviposition) of approximately 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.

Fig. 3
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.

Monitoring For Apple Maggot

When monitoring AM traps, AM’s 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 (mid to late June in upper Illinois). First emergence may be detected by checking traps daily until the first fly is spotted on the 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, capture of ONE AM on any one trap at a time 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.

Control for Apple Maggot

Several insecticides can be used for apple maggot control including those used for codling moth control like acetmaprid and/or spinosad.  Acetamiprid is a soft, conventional control and is available as  Ortho Flower, Fruit & Vegetable Insect Killer.  This is a ready to use product that contains .006% acetamiprid, a synthetic organic compound of the family of chemicals that acts as neonicotinoid insecticides. Acetamiprid is a contact insecticide for sucking-type insects and can be applied as a foliar spray or a soil treatment. Acetamiprid 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.

For additional information, see the following fact sheets which are available from local university extension services:

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