Winter moth frass on blueberry bud. Blueberry bud pulled apart and see caterpillar.
Check your apple leaves and buds for winter moth damage. It’s often easier to find frass than winter moth caterpillars. Most caterpillars I found today were inside stuck or folded leaves. See attached pictures. If you are finding much damage consider applying a Bt insecticide such as DiPel.
Damaged apple leaves from winter moth. Apple leaves pulled apart and see small caterpillars.