Karl Foord, Extension Educator - Horticulture
Plum Curculio (Conotrachelus nenuphar) is a pest that may be active now in your apple trees (Photo 1). The first damage caused by these insects is feeding (Photo 2) which creates a small hole (Photo 3). Although this hole is shallow (usually less than 1/8th of an inch, multiple such wounds can affect the quality of the fruit. One way to avoid this type of injury is to place nylon stocking maggot barriers on the fruit (Photo 4). See "A Different Way to Protect your Apples from Apple Maggot". Soon these beetles will mate and you will begin to see a different type of damage caused by the female cutting a crescent -shaped slit into which she will deposit her eggs. See photo 3 in this Plum Curculio Insect Identification Sheet.
The actual size of a plum curculio is @ 1/4 inch long, and the size of the apples in the photos is @ the diameter of a quarter.