There is probably no other pest as damaging to home fruit production as the apple maggot, a.k.a. railroad worm. The plant is native to this region of the world and is found throughout the state. The fruit infestation typically occurs during the summer when many families are taking vacations. Even a brief lack of attention can lead to substantial fruit damage.
Table of Contents
1. Biology of Apple Maggots
2. Devastation of Apple Maggots
3. Apple Maggot Prevention
4. Controlling Apple Maggots
5. Insecticide Chart
Biology of Apple Maggots
Apple maggot spends winter in the soil as a pupa. Adults emerge from the soil in late June or early July. Apple maggot flies continue to emerge from the soil throughout the summer and can be active until October. In the first seven to ten days following its emergence, the adult apple maggot feeds until it has reached sexual maturity. After mating females lay eggs just under the skin of the host fruit. A single female can lay between 300 and 500 eggs over her lifetime, which can last 30 or more days. Eggs hatch in 3 to 10 days depending on temperatures. The larvae (maggots) feed while tunneling through the fruit flesh. Typically larvae complete development in about 30 days. Temperatures and fruit hardness influence the rate of development and survivorship of larvae. Full-grown larvae leave the fruit and enter the soil to pupate. Most apple maggot pupae remain in the soil for one winter, though a few may remain there for two or more years. In warm years some flies can complete development and emerge as a partial second generation.
There are several factors that affect your ability to control these pests, such as how many apple maggots are present in an area and how many unmanaged apple trees surround your garden. You may have trouble keeping apple maggots under control if others in your area plant trees and don’t maintain them.
Devastation of Apple Maggots
Apple maggots are able to damage apples on two different levels. The first damage occurs when they lay eggs on the apples. The apple flesh stops growing at that site, which results in a weird, dimpled or sunken area on the apple—but it doesn’t stop there! When the maggots hatch, they tunnel through the flesh of the apple, causing it to decay and rot. Even so, a bit of prevention can help you defeat the destructive apple maggot.
There are several factors that affect your ability to control these pests, such as how many apple maggots are present in an area and how many unmanaged apple trees surround your garden. You may have trouble keeping apple maggots under control if others in your area plant trees and don’t maintain them.
Apple Maggot Prevention
Sanitation is the first issue to address. Pick up and dispose of apples within a few days after they’ve fallen. The best way to dispose of them is to trench compost them—just be sure that your trench or hole is at least a foot deep. If you still want to use these fallen apples, you can trim off the bad parts and turn the remainder into cider or applesauce.
Controlling Apple Maggots
Controlling apple maggots has been traditionally achieved with organophosphate insecticides, like Imidan. Synthetic pyrethroid compounds, like Asana, Warrior, Danitol, Battalion, Mustang Max and Baythroid, are also toxic to adult fruit flies but are generally viewed to be moderately effective because they have a shorter field residual.
- Red Sphere Traps will greatly reduce damage and work well to capture and reduce the number of egg-laying adults. Traps should be placed within the canopy just as trees are finished blooming. Hang spheres high in the brightest areas of the tree, 6-7 feet from the ground. Set out one trap for every 150 apples (2 traps per dwarf tree).
- Beneficial nematodes are microscopic, worm-like parasites that actively hunt, penetrate and destroy the pupal stage of this pest. For best results, apply in the early spring or fall around the base of trees, out to the drip line. One application will continue working for 18 months.
- Surround WP — made from kaolin clay — will suppress a broad range of insects and has shown over 90% control of apple pests. It also has a positive effect on fungal diseases like fire blight, sooty blotch and flyspeck.
- Apple maggot is listed on the labels of several reduced-risk and organophosphate-replacement insecticides:
- The neonicotinoids Belay and Assail are labeled for apple maggot control. Despite their limited lethal action on adult apple maggots, they provide strong curative action on eggs and larvae.
- Spinosyn compounds Delegate and Entrust are active against apple maggots when consumed, but have shown only fair control in field trials with high pest pressure, thus are marketed only to suppress apple maggots.
- OMRI-approved Venerate is a biopesticide used to control apple maggots.
- Pre-mix compounds such as Voliam Flexi, is labeled for apple maggot control.
