Wooly Beech Aphid Infestation in a Garden

Magnified Wooly Beech Aphid (via Wikimedia Commons, CC BY-SA 4.0)

Wooly beech aphid infestations are a common problem in gardens. These tiny insects feed on the sap of beech trees and can cause damage to both the leaves and branches of the tree. Over time, infestations can lead to stunted growth, yellowing leaves, and even death in severe cases.


  • Yellowing or curling of leaves
  • Stunted growth
  • Wilting of leaves or branches
  • Sticky residue or honeydew on leaves and branches
  • Sooty mold growth on honeydew deposits
  • Distorted or curled leaves
  • Increased ant activity
  • Deformed or stunted shoot growth
  • Reduced leaf size
  • Dieback of shoots or branches
  • Premature leaf drop

What is a Wooly Beech Aphid

  • Soft, white, cottony appearance
  • Round or pear-shaped body
  • Small (1-3mm) in size
  • Found in colonies on the underside of leaves and branches
  • Long, slender antennae
  • Black legs and eyes
  • Two pairs of wings, with the hind wings being larger and more membranous than the forewings
  • A tubular-shaped cornicle or tailpipe on their hind end
  • No visible eyes or distinguishable head

Treating a Wooly Beech Aphid Infestation

It may be necessary to use multiple methods to effectively control a wooly beech aphid infestation in a garden. For example, introducing beneficial insects can help reduce the population in the long term, while a chemical control method may provide quicker relief. It is important to monitor the infestation and adjust the control methods as needed to ensure complete control of the aphids.

Physical Control Methods

  • Rinse leaves and branches with a strong spray of water to knock aphids off. This method can help reduce the population but will not eliminate it completely. It is best used in conjunction with other control methods.
  • Use row covers to protect plants from new aphid infestations. The covers should be secured tightly to the ground to prevent aphids from getting in.
  • Remove and dispose of heavily infested plant parts. This will help reduce the aphid population and prevent the spread of infestation to other parts of the garden.

Chemical Control Methods

  • Apply insecticidal soap or neem oil to the infested parts of the plant. Insecticidal soap works by breaking down the aphids’ exoskeleton and causing dehydration. Neem oil is a botanical insecticide that works by disrupting the hormones of the aphids and preventing them from feeding and reproducing. It is important to follow the instructions on the product label and to reapply as needed.
  • Apply pyrethrin-based sprays. Pyrethrins are a group of compounds found in chrysanthemum flowers that are toxic to many insects, including aphids. Pyrethrin-based sprays are safe for use around people and pets but can harm beneficial insects, so it is important to use them judiciously.
  • Use systemic insecticides. Systemic insecticides are taken up by the plant and provide long-term control of the aphid population. They can be applied as a soil drench or as a foliar spray. It is important to follow the instructions on the product label and to choose a product that is appropriate for the type of plant being treated.

Cultural Control Methods

  • Provide adequate water and fertilization. Healthy plants are less attractive to aphids and less likely to become infested. It is important to water plants deeply and regularly and to fertilize them according to their needs.
  • Keep the garden clean. Aphids can hide in weeds and plant debris, so it is important to keep the garden free of these materials.
  • Avoid overcrowding plants. Overcrowded plants are more likely to become infested with aphids. It is important to space plants appropriately and to provide adequate air circulation.

Biological Control Methods

  • Introduce beneficial insects. Ladybugs, lacewings, and hoverflies are all natural predators of aphids and can help reduce the population.
  • Provide habitat for predators and parasites. Planting flowering plants can attract beneficial insects to the garden and provide them with the resources they need to thrive.
  • Use biopesticides. Biopesticides are naturally occurring substances that are used to control pests. Beauveria bassiana is a naturally occurring fungus that can control aphids. It is applied as a spray and infects the aphids, killing them.