Tree Fruit Research & Extension Center

Cullage Assessment & Education

Quick Identification Guide to Apple Postharvest Defects & Disorders Cards

Arthropod Damage

The Arthropod section of the card set includes all the major insect damage found in Washington apples. This section also includes some mite damage. At a later date more cards may be developed for this section which would include other forms of animal damage, such as, bird pecks and rodent feeding, as well as, any emerging or reclassified disorders. Click on the tab below for the pest damage you are interested in viewing. For ordering information visit the Order Information section of Introduction. The cards shown on this site are slightly modified to accomodate web formatting. Figures may appear fragmented in some browsers. Please report viewing problems here. Any reproduction of the card images or content without permission is in violation of WSU Copyright policies.



ARTHROPODS: Aphids & Mealybugs  

Wolly apple aphid

Aphids and mealybugs are closely related insects. Normally, they infest the vegetative parts of the tree. However, with a heavy infestation, the insects move on to the fruit from the stem, or they may crawl over from leaves touching the fruit. Wooly apple aphid (WAA), Rosy apple aphid (RAA) and Grape mealybug are those most commonly found in the Pacific Northwest. Species identification is made by an entomologist or trained fieldman.

Figure 1: The insect may find its way inside the fruit. Shown here are two WAA, one smaller purplish nymph above the seed, and a “wooly” adult below and to the left.  
WAA external

Figure 2: Two WAA nymphs deep in the calyx. Aphids can enter the seed core this way.

Figure 3: Frequently, fruit infested with aphids or mealybugs have sticky honeydew, a by-product of feeding. Shown here are two mealybugs. The shiny areas on the fruit are from honeydew. Honeydew is a good growth medium for fungus, such as, sooty mold. Presence of sooty mold should alert you to the possibility that the fruit lot came from an infested orchard block.




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