Washington is well-known for its prolific production of apples. Though it tends to be an easy crop to grow with a joyful harvest, the proliferation of a new apple pest requires a little more vigilance for a successful crop.

Who’s the Culprit?
Apple maggot adults look like small flies with striped wings (see below).

Adult apple maggot

Adult apple maggot.
Source: Washington Department of Agriculture

Why Be Vigilant?
Apple maggots lay their eggs just under the skin of the apple so that when the larvae hatch, the young insects can feast on the fruit as they grow bigger. This means brown, mealy apples for you. Apple maggots also lay eggs on crabapples and English hawthorn fruit, primarily from July to August.

Thinking About This Pest Holistically
Apple maggots are insects that originate in Europe and have not evolved in concert with the flora and fauna of the Pacific Northwest. Therefore, repelling and killing these insects does not harm their survival and ecological niche in their place of origin.

The Washington State Department of Agriculture has been working hard to keep apple maggots out of this region. Nevertheless, populations of apple maggots have been reported. We recommend monitoring as a preventative plan.

One simple technique is to monitor for apple maggots by hanging a sticky apple trap from a branch when you expect the flies might be present, July through August in the Pacific Northwest. These traps are red and round to resemble an apple, and contain a scent to lure the flies. The surface contains a sticky substance that traps the flies so they’re not able to fly away. Hang the trap in the canopy of the apple tree and check it periodically when adults are likely to lay eggs.

A species-specific insect trap

Apple maggot fly trap.
Photo source: Raintree Nursery

You Caught Apple Maggots – What Do You Do Now?
If you have apple maggots and are motivated to protect this year’s crop, place a small stocking over each fruit to protect the flies from penetrating. This definitely requires time and comfort with ladders. If you’ve been carefully monitoring your trap, then you likely will preserve much of the harvest.

For the following year, apply kaolin clay to the entire canopy just after petal fall. Kaolin clay is an organic material that acts as a physical barrier to the flies, but easily washes off after harvest. You may need to reapply after a hard rain if you’re still in the critical window of the egg-laying season. This is something you can do on your own, or call us if you need help.

Cheers to the sweet juice of homegrown apples dripping down your chin! What a joy!