Walnut Aphid
Chromaphis juglandicola
7 host plants
Last updated
Data Coverage 1 of 6 dimensions
Walnut aphids are small, dark insects that congregate on walnut leaflets, causing leaf yellowing and wilting due to sap feeding. Honeydew production promotes sooty mold growth and attracts ants. Infestations typically develop by midsummer on walnut trees in warmer regions, though occurrence is uncommon in cool-climate walnut plantings.
For landscape walnuts, prune to improve air circulation and reduce aphid habitat. Spray insecticidal soap targeting leaf undersides when populations first appear. Encourage parasitoid wasps and predatory beetles by maintaining flowering plants nearby. In cool-climate regions with limited walnut cultivation, aphid pressure is typically minimal.
Quick Reference
Order
Hemiptera
Type
sucking-insect
Host Plants
7
Cultural Controls
- Encourage natural enemies including ladybird beetles, lacewings, syrphid (hover) fly larvae, and parasitic wasps.
- Avoid use of broad-spectrum insecticides which kill beneficial insects.
- Hand-wipe or prune to control small, localized infestations when practical.
- Wash aphids from tree with a strong stream of water.
- Control honeydew-feeding ants, which may protect aphid colonies from predators.
- Provide proper nutrition.
Host Plants (7)
Aleurites moluccanus Candelnut, Kukui, Indian Walnut Juglans ailantifolia Japanese Walnut, Heartnut Juglans californica California Walnut, Southern California Walnut Juglans cinerea Butternut Juglans microcarpa Texas Walnut, Little Walnut Juglans nigra Black Walnut Juglans regia English Walnut, Persian Walnut