Apple maggots are the most annoying and destructive pests for those of us who grow our own apples. Unfortunately, part of the formula as to whether you'll be successful in controlling these pests is dependent on other factors, such as how many apple maggots are in the area in a given year and how many unmanaged apple trees are around your garden. If you live in an area where others are also growing trees, but they don't maintain them, you may have a tough time on your hands keeping apple maggots under control.
Apple Maggot Damage
Apple maggots throw a one-two punch when it comes to causing damage to our apples. 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 they don't stop there! After the maggots hatch, they tunnel through the flesh of the apple, which causes the apple flesh to break down and rot.
Preventing Apple Maggots
Keep It Clean
The first issue to tackle is sanitation. Be sure to 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, like many who grow apples, still want to make use of these fallen apples, you can trim away the bad parts and turn the remainder into cider or applesauce.
The next thing to work on is trapping. The best traps for trapping adult apple maggots are red sticky ball traps. You hang these in the tree, and the adult apple maggots think they're a nice, large apple to lay eggs on...and get stuck to them instead. No more egg laying for them! You'll want to use a trap that has a pheromone attractant with it. This makes even more adult apple maggots attracted to the traps. These traps and the pheromones are available in garden catalogs, nurseries, and online. are available in garden catalogs, nurseries, and online.
You'll want to hang one trap for every one hundred apples on your tree, spaced fairly evenly throughout the canopy. For most trees, five traps should do. Be sure to hang your traps as soon as blossoms drop and the tree begins to set fruit. Check the traps regularly to replace pheromones or clean off those that are full of insects and other gunk—they work better the cleaner they are.
Even if you have unmanaged trees in your area, and it seems like you'll never get rid of the maggots, there is one tried-and-true method of ensuring you get some apples: bagging. If you thin the fruit, then place a plastic bag over each apple when it's small (before the maggots emerge in early summer) they won't be able to lay eggs on them. If they can't lay eggs, then you'll have undamaged apples! You can use a zipper-type plastic sandwich bag, or any other small bag that you staple or tie around the apple's stem. No matter which type of bag you use, be sure to poke or cut small holes in the bottom so that any moisture can drain out of the bag. They will need to be bagged all season because the adults are present all season long. The tree may look funny, but at least you'll have perfect apples at harvest time.
With a bit of work and a bit of prevention, you can defeat the destructive apple maggot, and have plenty of crisp, perfect apples from your very own garden.
Apple Maggots in Home Orchards. University of Minnesota Extension Website