Linden(Tilia): Linden aphid

Biology

Basswood or linden (Tilia spp.) trees planted along streets and in parking lots are commonly infested with linden aphids. The linden aphid feeds in colonies on the underside of leaves. Wingless aphids are green with black stripes or dots across the abdomen. Winged adults are similar in appearance, with black markings on the wings. Feeding damage from the linden aphid is usually minor, but can cause some leaf or shoot distortion if populations are very high. These aphids produce large amounts of honeydew, a sweet, sticky material. It can attract honeydew-feeding ants, which protect aphid colonies from predators. Honeydew may also promote an unsightly growth of black false sooty mold. Honeydew and false sooty mold can be a nuisance, particularly in street or parking lot plantings, but does not harm the tree.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Wash trees with a strong stream of water to knock down aphids and wash away honeydew.
• Hand-wipe or prune to control small, localized infestations (when practical).
• Encourage aphid predators and parasites, including ladybird beetles, lacewings, and parasitic wasps. Avoid use of broad-spectrum insecticides which may kill these beneficial insects.
• Provide proper nutrition. High levels of nitrogen in the foliage encourage aphid reproduction. Use a slow-release or low-nitrogen formula if fertilizer is needed.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Do not make applications to blooming trees, as linden is very attractive to bees.
• Do not use soaps on trees stressed by drought or heat.
• Do not apply soaps in full sun or when temperature exceeds 90 degrees F.
• Dormant or delayed-dormant application of horticultural oils will help manage overwintering aphids and/or eggs.
• Homeowners should not make foliar applications to trees over 10 feet tall.
• Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 feet tall.
• CAUTION: These pesticides are toxic to bees.
• To reduce risk to pollinating bees, make pesticide applications in the evening after bees are done working for the day.
• Do not apply on or near flowering plants.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

• All Seasons Horticultural and Dormant Spray Oil Concentrate [Organic]
  Active ingredient: mineral oil/pet distillate [EPA registration number: 4-80]
• Foxfarm Don't Bug Me Home and Garden Insect Spray RTU
  Active ingredient: pyrethrins, piperonyl butoxide [EPA registration number: 1021-1801-71996]
• Gordon's Dormant Oil Spray
  Active ingredient: oil/pet distillate [EPA registration number: 33955-458]
• Safer Brand Insect Killing Soap Concentrate II [Organic]
  Active ingredient: potassium salts of fatty acid [EPA registration number: 42697-60]
• Whitney Farms Insecticidal Soap [Organic]
  Active ingredient: potassium salts of fatty acid [EPA registration number: 67702-21-73327]
• This list may not include all products registered for this use.

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