WSU Whatcom County Extension

Apple Leaf Curling Midge

Integrated Pest Management     

Close up of sticky trap

WSU Research



Leaf damage can easily be seen visually; break open the curled leaves to find larvae. Trees can tolerate a certain amount of damage. This pest is mostly an issue on newly grafted trees, where it can destroy the terminal end and destroy the grafted plant.


A new pheromone, developed in the UK, was tested as a monitoring tool in 2009 at 4 farms in Whatcom and Skagit Counties. It was very effective at catching male ALCM (the females are not attracted to the pheromone); the adults can be distinguished as having bright red pools of heamolymph at the end of their long legs after trapping.

Flies on a sticky trap

Photos of trapped adults by Jerry Cross, East Malling Research

The traps caught many ALCM; in some weeks over 1,000 midges were caught at each trap. Traps were put out following first emergence in 2009 so we were not able to know the total peak numbers of the pest (figure 1). The first generation has the largest peak of adults emerging at once. Generations #2 and #3 have fewer adults emerging at once. Life cycle timings can vary slightly between individuals which allows for a more spread out emergence of adults for generations 2 and 3. Also, spirotetramat (Ultor/Movento), a systemic pesticide was used at one farm to treat the pest near the end of the first adult emergence which may have reduced the number of surviving larvae in generations 2 and 3 (figure 3).

In 2010, we put traps at 2 locations in Whatcom County to try to determine the timing of first emergence (figure 2).


Using Pheromone Traps as Control

Measurements on the number of galls per plant were made on plants right at the trap and plants located at set distances from the traps. This was done for both the control and pheromone traps to determine if the pheromone traps reduced the number of galls on trees close by.

There were no significant reductions in population size due to the pheromone traps.

Figure 1: Total Adult Male Midges Caught Per Day (pdf)

Figure 1

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Figure 2: Average Adult Male Midges Caught Per Day at 2 sites (pdf)

Figure 2

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Figure 3: Farm A Average Adult Moth Catch With Pheromone Per Day (pdf)

Figure 3

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Whatcom County Integrated Pest Management


"Integrated Pest Management, IPM, is a decision making approach to pest management that involves knowing the crop, the pest, the ecosystem, and the relationship between all of these components."




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WSU Whatcom County Extension • 1000 N. Forest St., Suite 201, Bellingham, WA 98225 • (360) 778-5800 •