Apple Maggots Controlled

What are apple maggots, and how can one get rid of them?

The apple maggot fly pierces a hole in the apple skin in order to deposit its eggs which in turn becomes a larvae, a maggot, that tunnels its way throughout the apple as it feeds. These larvae are known as apple maggots (also referred to as railroad worms). The apple maggots produce one to two generations each and hibernate in the soil as brown pupae.

The maggot flies lay their eggs in the flesh of usually sweet or subacid, thin-skinned apple varieties that ripen during the summer or early fall, and the legless apple maggots develop in the flesh of the fruit.

To avoid having your apples destroyed by apple maggots, as an apple grower you must 1) recognize the pest, 2) know what damage apple maggots cause, 3) understand the life cycle of these apple maggots, 4) recognize when apple trees are being attacked by apple maggots  or the apple maggot fly, and 5) know how to control and/or stop infestation

1) Recognizing the apple maggots and the adult fly pest:

apple maggot fly To get rid of apple maggots, you must first know what the fly looks like.

The apple maggot fly is about 5mm or 1/5 inch long. It is somewhat smaller than a house fly, has a white dot on its thorax, and on its wings it has a band of black that looks like an F (some say it looks like a W.)

The presence of larvae, or apple maggots, is the part of the apple maggot cycle which causes the damage to the fruit.  The larvae looks like a typical fly larva or maggot left on rotting meat or fish.

The apple maggots are very small, pale cream colored worms that feed on the “flesh” of the fruit as they tunnel their way under the apple’s skin.  Apple maggots have no head section or legs, have a wedge-shaped body, and have two small black hooks extending from the pointed “head” end when feeding

2) How apple maggots damage the fruit:

Apple maggots tunneling under the apple skinWhen a maggot fly lands on the apple, it pierces a hole in the skin of the apple and lays its eggs one at a time. Where eggs have been inserted by the female fly just under the skin, you will notice small dimples and hollows.
As time progresses, the apples will appear full of bumps as the apple matures.  You can see distinctive brown tunnels made by these apple maggots as the meander through the flesh of the fruit.

If left unchecked, infested apples soften, turn brown, and prematurely fall to the ground.  At that point, the apple maggot leaves the fruit and buries into the ground to overwinter and morph into a pupa.

Wouldn’t it be a good idea to have nematodes in the ground getting rid of the pupae before it turns to a fly which creates these apple maggots?   You can read all about nematodes towards the end of the article in the post Natural Lawn Grub Control .

3. The life cycle of the apple maggots

According to the Washington State University, the life cycle of the apple maggots are as follows:

a. In late June/early July until early October, flies begin to emerge from the pupae which have overwintered in the ground under previously affected fruit trees.  Their peak time is August.

b. After 7 to 10 days of feeding themselves on aphids, bird droppings, or even drops of sap from trees or other plants, the flies responsible for creating  apple maggots become sexually mature and mate.

c. Females then look for and lay their eggs on ripening apples.  They will go from tree to tree as fruit ripens.  This means that if one apple variety ripens later than another, the apple maggot fly will go from one variety to the other.

d. The female lays its eggs one at a time just under the skin of the fruit.  These eggs will hatch in 3 to 7 days. During its lifetime of 2 to 4 weeks, a female can lay up to 500 eggs.

e. apple damage by apple maggotsDepending on the temperature, the apple maggots (larvae) mature in 13 to 50 days.  During that time it tunnels through the fruit flesh and leaves behind bruising and decay until the fruit finally falls to the ground.

f. If the fruit falls to the ground, the apple maggots leave the fruit and burrow into the soil to overwinter.  There each one turns into a pupae ready to emerge as a fly in the spring.  Any apple maggots which remain in unharvested fruit on the tree will probably not survive the winter.

4. Recognize when apple trees are being attacked by apple maggots  or the apple maggot fly

If you notice that some apples are dimpled outside and have brown tunnels inside, then your fruit are being eaten by apple maggots. That means that the apple maggot fly is using your orchard to lay its eggs. These small dimples and depressions will appear where females insert their eggs under the skin of the fruit. Apples which have been infested by apple maggots early in the season will appear bumpy as they mature.

5. Control and stop infestation of apple maggots

What to do?

** The most effective homemade traps is to make red sticky ball traps. Use a red or black plastic or wooden ball about three inches in diameter (a little bigger than a real apple) and attach a wire to the traps.   Hang these red spheres or plastic fruit coated with Stickem or Tanglefoot (a commercial tacky product) in apple trees to attract and trap female flies.

traps for apple maggotsHang sticky balls at eye level about 2 to 3 feet from the tips of the branch. (By the way, these traps are readily available from the gardening stores or gardening catalogs)
Keep the foliage and real apples away from the sticky traps so that the traps are visible.
Hang two traps in each dwarf tree and four to six traps in full-sized trees.
Wipe dead insects off sticky traps and recoat them as needed.

** You can trap flies before they can do damage by mixing one part blackstrap molasses or malt extract to nine part water. You can add yeast to encourage fermentation, and pour into wide mouthed jars and hang from trees limbs.

** If you want to monitor the fly population, use bait made of 2 teaspoons household ammonia and 1/4 teaspoon soap powder in a quart of water. Hang the jars about shoulder height on the sunny side of the trees throughout the orchard.

A dozen jars should be enough in providing you with an accurate picture of the fly activity. Examine the flytraps every two to three days to keep a count.

The bait should be changed at least once a week.

** Pick up and remove fallen apples once to twice a week to reduce the apple maggot population on the ground. You can feed the dropped apples to livestock. Apple maggots in fruits may be killed by placing the fruit in cold storage at 32°F for a period of 40 days; if the fruit is not too seriously injured,it can be used for apple cider.  If however you want to bury the apples in the ground, remember that the pupae hibernate in the ground, so bury these apples at least one foot deep.  (I would probably use a shovel and chop through these apples to kill as many maggots as I can)

** Remove wild crabapples and hawthorns, which can be carriers of apple maggots, from within 300 feet of your orchard.

You can detect the first emergence of adults by hanging yellow sticky traps in abandoned orchards or unsprayed apple trees in infested areas. To detect the beginning of egg laying, hang red sticky spheres in apple trees, then treat as soon as the first fly is found.

In Oregon, where some orchards are treated regularly for apple maggots, the first maggot spray is applied seven to 10 days after the first fly has emerged. Later sprays follow at 10 to 14 day intervals as long as adults are active and are being caught in traps.

However, I still think that if you used the homemade fruit tree spray from the very beginning in early spring before the budding of the trees and keep spraying evey 10 to 14 days, the problem with apple maggots should disappear.

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