- Inspect your trees once a week beginning in April. The best time to treat your trees for balsam twig aphids is just prior to reproduction. Check the undersides of the needles and branches. Look for a few pale green, wingless aphids feeding or for signs of aphid damage, such as curled and bent needles. This first generation of nymphs will develop into wingless aphids over time and give birth to the live nymphs that can damage the tree. When they are visible and beginning to swell, it is time to treat the tree.
- Begin by spraying the tree with water. Place a spray nozzle attachment on the end of a garden hose to create a high pressure stream. Turn this spray on the tree, focusing on the underside of the branches and the main tree trunk. The power of the water will dislodge most of the aphids and carry them away.
- Once you have watered the tree, spray it again with an insecticidal soap. Add a few teaspoons of detergent and a cup of vegetable oil or mineral oil to a bottle of lukewarm water. Shake the bottle gently to combine the ingredients and spray the tree, thoroughly coating each branch. This clogs the aphid's airways and can be safely applied once a week. Do not apply this particular remedy on a hot, sunny day. The oil will magnify the radiant effects of the sun and can burn the plant tissues. If you must treat the tree and there is not a cloud in the sky, leave the oil out. The detergent works as a dehydrating agent and is therefore an effective remedy on its own.
