Description and Biology
Several species of woolly oak aphids, Stegophylla spp., are found on red oaks in North Carolina. These small, pale aphids secrete a fluffy substance from which their common name is derived. Not much is known of the biology of Stegophylla aphids. The aphids are usually noticed in mid to late spring because they cause the leaves to curl to form a shelter in which these aphids feed and reproduce. Although this damage is unsightly, it does not seem to affect the overall health of the trees. In severe cases they may cause leaf curl with obvious patches of woolly-looking secretions in the leaves. These aphids probably have alternate hosts.
Woolly oak aphids cause the leaves of various red oaks to curl noticeably in spring.
This is typical damage caused by woolly oak aphids.
Host Plants
Willow oaks, red oaks, and live oaks are the most reported hosts of woolly oak aphids. The majority of records for Stegophylla brevirostris in Florida came from live oak (a few records came from other species of oaks).
Residential Recommendation
By the time woolly oak aphid damage is noticed, it's usually too late to corrrect damage by woolly oak aphids for the current year (Applying an insecticide will not uncurl the leaves.). If one is compelled to try and eliminate the aphids, small trees can be sprayed with water from a garden hose. That should dislodge and drown many of the woolly oak aphids. Horticultural oils or insecticidal soaps are also effective, but spraying large trees may be difficult, expensive, and certainly not worth the effort.
References
- Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide. 3rd edition. Dreistadt, S. H. 2016. U. of California Agr. and Nat.l Resources pub. 437. pp.
- Aphids on Ornamental Landscape Plants. Steven Frank. 2009. Entomology Insect Notes, NC State Extension.
- Woolly oak aphids in Florida (Hemiptera: Aphididae). Halbert, S. E. 2013. Entomology Circular No. 427, Florida Dept. of Agr.and Consumer Serv., Div. of Plant Industry.
- Extension Plant Pathology Publications and Factsheets
- Horticultural Science Publications
- North Carolina Agricultural Chemicals Manual
For assistance with a specific problem, contact your local Cooperative Extension Center.
This Factsheet has not been peer reviewed.
Publication date: July 22, 2013
Revised: Oct. 23, 2019
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