Living With Apple Maggot

Apple Maggot Fly
Image: Joseph Berger

Apple maggots are pests of apples in the Eastern United States where active control measures are necessary.  Apple maggots overwinter as pupae, lay eggs on apples in summer and pupate in the soil in fall. The apple maggot can develop on a several plant species including horticultural plants. The apple maggot is a North American species that became a pest of apples when it moved from hawthorne to apple in the 1860s. Apples are not native to North America, but other plants in the family Rosaceae such as hawthorne are native.

In apple production areas of the western US such as Washington [state], the apple maggot has not been a pest. Apple maggot arrived on the west coast in 1979 (possibly by someone moving infested fruit) where it has established. Quarantines are in place to prevent movement of apple maggot into the apple growing regions of eastern Washington.

Of particular concern is the handling of “Municipal Green Waste”. Urban areas on the west coast need to dispose of plant waste: leaves, brush, twigs, limbs and old fruit. Composting  green waste is a cost effective measure to recycle nutrients.  Demand for composting has out paced local composting capacity.  This led a company to build a composting facility for Seattle compost east of the Cascades in an area where apple maggot is not found. Discoveries of apple maggot at the compost facility resulted in closure of the facility. A risk analysis concluded that the threat to the apple industry was real and made recommendations as to how municipal green waste might be treated to exclude apple maggots.

This is one more example of how integrated our ecosystems are. Practices that are good for urban areas may adversely affect agricultural areas and agricultural practices can adversely affect urban areas. It is important to have a view of the whole ecosystem rather than exclusively focus on a narrow component in order to prevent bad outcomes.