After pruning your trees, you may want to consider applying a dormant-oil spray to kill insect eggs and larvae overwintering on the twigs and bark of your trees. Three types of insects in particular can be controlled with careful dormant-oil spraying: aphids, which lay eggs on tree bark, peach tree borers, which overwinter as larvae; and that foe of apple, pear, and walnut growers, the codling moth, which overwinters as pupae.

Dormant-oil works by suffocating the pupa, larva, or egg of the insect. It works only on pests that overwinter on the surface of your tree and it has not been approved by the FDA for use on all fruit and nut trees so it is important to read the label on the dormant-oil spray carefully. Your tree must be fully dormant at the time of spraying and you'll save money by spraying after pruning because you'll have less tree surface to cover. Check your local nurseries or garden suppliers for different brands of dormant-oil (Volcks Oil is one), and remember to read that label carefully!