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There really is nothing like growing, picking, and eating fruit, directly from the tree. It’s delightful to eat the fruits of your labor. After a season of growing apples, there’s nothing like taking that first bite of a ripe fruit.
It’s not so great when you bring the apple to your mouth, just to encounter the apple maggot or the damage it has left behind.
Apple maggots are common and extremely destructive. Let’s talk about how to deal with this unwanted guest.
What Are Apple Maggots?
Apple maggots, also called railroad worms, are the offspring of a fruit fly called Ragoletis pomonella. Don’t confuse apple maggots with Phrixothrix beetle larvae, which are also called railroad worms.
You might confuse them with codling moths (Cydia pomonella), as well. These maggots also feed on the inner flesh of the fruit, but they leave long tunnels with frass inside. snowberry maggots (Rhagoletis zephyria) look similar but they don’t feed on apples.
Native to the northeastern US where they fed on apple relatives like hawthorns (Crataegus spp.), they have spread across North America.
When Europeans imported apples and began cultivating them across the US, the apple maggot fly couldn’t resist and swapped preferences. Instead of feeding on crabapples (Malus spp.) and hawthorns, it started favoring domesticated apples (Malus domestica).
It took around 150 years after the introduction of domestic apples, but now this pest is a widespread concern and responsible for huge losses, both in commercial orchards and for the backyard grower.
How to Identify Apple Maggots
Maggots can be a problem for any apple grower in the US. They prefer apples, but can adapt to other fruits, namely cherries, plumsand pears. Of course, crabapples and hawthorns can also act as hosts.
From the outside, an apple may appear pristine; only when cut open or you take a bite can the maggot horror reveal itself. Or, the skin may show evidence of the attack.
Understanding the lifecycle and behavior of apple maggots is crucial in controlling and preventing infestations.
This pest is more active when conditions are both warm and humid. Temperatures around 50°F are best for development and reproduction. The cycle typically begins in late spring, once the overwintering young emerge as adults.
Female adult flies lay tiny, white eggs on the surface of the fruit, usually in small crevices or blemishes, during the summer months. In about 7 days, they hatch. Once hatched, the larvae burrow into the fruit, eating it from within.
The maggots are typically creamy-white in color and measure a quarter inch long.
The maggots don’t have a distinct head, which is one reason they can be mistaken for worms rather than maggots. They have two black hooks for mouth parts that they use to feed on the flesh of the host fruit.
This stage lasts four to six weeks, during which they go through three instars before dropping to the ground, ready for the next transformation.
The apple maggots drop from the fruit and tunnel into the soil. Their outer skin hardens and darkens to a brown shell. Metamorphosis occurs in about two to three weeks. Once complete, the adult fly pushes out of the cocoon and leaves the soil.
The adults are about a fifth-inch long and have distinctive zebra-like patterns on their bodies and wings. This pattern is meant to mimic the look of a jumping spider to help protect them from predators.
Females are able to reproduce and lay eggs about four days following emergence. She is capable of laying approximately 400 eggs in her life.
Adults live for up to three weeks and feed by inserting sucking mouthparts into the skin of the fruit. This feeding leaves speckling behind
Signs of an Apple Maggot Infestation
Watch out for the signs of a potential apple maggot outbreak so you can act quickly to save your harvest. Any hint that apple maggots have come to dine requires swift action to curb damage and losses.
1. Damaged Fruit
One of the most obvious signs of an apple maggot infestation is damaged fruit. As the apple maggots feed on the flesh of the fruit they create tunnels and burrows. This causes the fruit to become distorted and misshapen.
In the case of apples, browning of the flesh can occur due to the bruising effect of the bites and the apple’s oxygenation response.
On the surface of the fruit will be tiny puncture wounds. These are the entry points of the apple maggots once hatched and the adult feeding marks. When the skin is punctured, oxygen enters the fruit and causes decay. With this, some fruit may appear to ripen early.
2. Premature Fruit Drop
Damage caused by the eating of fruit’s flesh triggers premature fruit drop. When fruit is damaged or diseased, the tree will opt to abort it before it’s mature. This can occur at any point of the fruit’s growth and is dependant on the stage of the infestation.
The more mature the larva, the more damage they do to the fruit. The more apple maggots present in that fruit, the quicker premature fruit drop may happen.
3. Pest Presence
By the time you see fruit drop or damage on the fruit, it’s too late to save those particular apples. So identifying the pest and stopping it from laying and feeding is the best way to prevent the loss of your harvest.
The adult can stay under the radar most of the time because it’s so small. However, with a keen eye and knowledge of your plants, you can keep a closer eye out. But don’t rely on catching them in action. Hang yellow sticky traps in the tree to catch them.
This won’t reduce the pest numbers but you will know for sure that they are present and can take action.
Maggots dropping out of fruit, crawling out of dropped fruit, and burrowing into the soil are other signs that there is a big problem. But at this point, it’s too late to save this year’s apples. All you can do is work to save next year’s fruits.
How To Prevent Apple Maggots
In order to be able to control this pest, several tactics need to be implemented. Remember, if the pests have already gotten into your apples, you can’t fix them at this point. The goal here is to break the generational cycle and keep next year’s crop safe.
You can also incorporate these steps to protect your crop even if no sign of pests are present.
1. Hygiene
Remove all fallen fruit and plant debris as soon as possible. Don’t leave fruit and leaf debris on the ground because this provides a place for the pests to hide and overwinter. Dispose of the debris, don’t compost it.
2. Monitor
Look out for the signs we’ve mentioned in this article and use yellow sticky traps to tell you when the adults arrive. If they do, there are steps you can take to prevent them from laying eggs.
3. Traps
Utilizing traps is an opportunity not to be missed. They assist in monitoring potential numbers of this pest while controlling numbers. You shouldn’t rely on traps alone, but they can be a good supplement.
Look for pesticide-free traps like those from Catch Em, available at Amazon.
4. Bagging
Bagging helps to prevent an in the first place, with the added bonus of preventing codling moths, as well.
This method involves covering each fruit on the tree with a mesh bag. It is a labor-intensive solution, but it is valuable for disrupting their lifecycle and protecting your harvests. Pick up 100 bags at Amazon.
5. Treatment
Treatments should always be as natural as possible. Chemical-based sprays can negatively impact the balance of the garden environment and may harm beneficial species.
The good thing is that apple maggots are easily targeted with natural treatments when applied regularly and correctly.
Neem oil and insecticidal soap can be used as a mild preventative by killing adults. Kaolin clay spray can discourage the adults from laying eggs.
Sprinkle diatomaceous earth around the trees to kill any falling maggots.
For severe infestations, insecticides containing sevin can be useful between June and September to try and kill the adults, but they aren’t recommended. These harsh chemicals probably won’t keep an infestation completely away, but they will also kill beneficial insects.
6. Biological Control
Encouraging natural predatory insects into the orchard or growing space will help keep the numbers of apple maggots, pupae, and adult flies in check.
Having a healthy, balanced environment for the trees and fruit to grow is essential. Predatory wasps, birds, lacewings, ladybugs, beneficial nematodes (Steinernema feltiae), and trichogramma wasps are all helpful.
Products that contain the beneficial fungus Beauveria bassiana can be used to kill the maggots. Pick up some BotaniGard 22WP and spray plants at the first sign of adults.
7. Plant Care
Keep trees healthy all year round with proper maintenance, pruningand feeding. This can help the trees ward off unwanted attention, but will also help them recover from any attack. Of course, it won’t fix infested fruits, but it will help your trees survive.
When you harvest apples to store for later consumption, inspect the fruit thoroughly. Toss out infested or eaten fruit because they will just rot.
