How to Control Woolly Aphids in Tall Trees at the Ground Level

It takes a severe woolly aphid infestation to even moderately harm a tall, mature tree.

Aphids are common pests on ornamental trees and low growing leafy plants. There are numerous species of the pest, which is a sucking, soft bodied insect. Aphids do their damage by sucking the sap from trees which can cause leaf drop and diminish the health of the plant. Woolly aphids occur on hardwoods, conifers and shrubs. The tiny 1/8 inch pest has white filaments covering its body which give it a fuzzy appearance. Woolly aphids overwinter as eggs in the bark of trees and one female can produce hundreds of offspring. Biological and systemic methods of control are most useful on trees too tall to spray.

Things You'll Need

• Long handled pruners
• Ladder
• Hose
• Hose end adjustable attachment
• Lady beetles
• Systemic insecticide (Acephate)
• Soil injectors

Instructions

1. Try multiple non-chemical methods before you use an insecticide which can be harmful to the environment and kill beneficial insects. Prune out any branches that you can reach with long handled pruners. This reduced the adult population that produces the second generation and will minimize the harm to the tree.

2. Use a hose and blast the soft bodied bugs out of the tree. A hose end attachment that has several settings is useful. Set it on the longest range spray the nozzle is capable of and hit the leafy areas of the tree as well as the wood. Pay special attention to terminal ends where tender new leaf and flower buds appear. This is favorite terrain for woolly aphids.

3. Purchase a bag of live lady beetles which can be found at most garden centers in late winter and early spring. Release the insects at the base of the tree. They are voracious predators of wholly aphids and will reduce the population significantly. If they are well fed, the beetles will lay their eggs in the tree for a second season of natural control.

4. Apply a systemic insecticide as a last resort. Systemics leach into the soil and are taken up by the tree's roots. The chemical travels through the tree's vascular system and will infest each part. The feeding behavior of the aphids will ensure they digest the poison and are killed. The problem with systemics is they are non-selective for the most part and can kill off beneficial insects that feed on the aphids.

5. Inject the soil around the tree with Acephate. You need .66 to 1.33 pounds per acre. The product is mixed with water and applied around the base of the tree with injectors that you can purchase with the product. Many formulations are available that are already measured and in injectors. It is a fast acting chemical and will persist in soil for about three weeks.

References

• Organo Lawn; Orthene Acephate
• "University of Minnesota Extension"; Woolly Aphids on Trees and Shrubs; John F. Kyhl, Jeffrey Hahn; October, 2002
• University of California Davis IPM Online; Cole Crops Other Aphids
• University of Rhode Island Greenshare Fact Sheets; Aphids