Codling moth worms in your apples.
If you grow apples in your backyard, chances are you’ve seen what these little fruit miners can do to your apple crop. With up to three generations a year, it is a challenge to control them and requires a multi-pronged approach. A combination of mechanical, biological and chemical methods is your best hope for meaningful control.
Choosing a dwarf rootstock is a great way to start out. Smaller trees are easier to pick, giving you a chance to remove and destroy infested fruit. You can prune more safely without using your rickety ladder and small trees are easier to spray as well. Some growers are bagging newly formed fruit to physically block the moth from laying eggs on the apple, removing them a couple of weeks prior to harvest to allow color to appear. Chemical control of codling moth requires up to six treatments, two for each potential generation, starting after petal fall and continuing through August.
At the very least, infested apples should not be left on the ground as worms can emerge from them and continue the life cycle.
Here is a bulletin from WSU with more detailed information: