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. The upcoming revision of the Defects & Disorders Guide may include additional forms of damage, such as bird pecks and rodent feeding, as well as, any emerging or reclassified disorders. To navigate directly to the pest damage of interest use the links below this text block.  The card images shown on this site are slightly modified from their original form to accommodate web formatting. Any reproduction of the card images or content without permission is in violation of WSU Copyright policies.

Codling moth    Leafrollers     Other caterpillars    True bugs    Aphid & mealybugs    
Scale, thrips & others

Codlin Moth

Codling moth (Cydia pomonella; CM) has become a serious quarantine pest for exporting apples. Some countries, such as Taiwan and China, require additional sampling to ensure that fruit are codling moth free prior to packing.


Two species of leafroller (LR) are common to the Pacific Northwest: Obliquebanded LR (Choristoneura rosaceana; OBLR) and Pandemis (Pandemis pyrusana). Both feed primarily on foliage, but fruit damage can occur when the foliage touches the fruit.

Other Caterpillars

Cutworm” is a general term referring to noctuid caterpillars, such as fruitworms, cutworms, and armyworms. Normally they feed on weed hosts, but they may move freely between weeds and apple trees. Severe fruit damage can occur while they feed on leaves that are close to apples.

True Bugs

There are three major Hemiptera (family of true bugs) that may cause feeding damage on apples: Lygus (Tarnished plant bug), stink bugs and Campylomma (Mullein plant bug).

Aphid & Mealybugs

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.

Scale, Thrips, and Other Insects

There are several other insects that may only occasionally cause fruit damage. However, if present, they could cause quarantine problems at some export destinations.