Aphids / honeydew on oak trees - Ask Extension
I read the Extension page about aphids. Every summer, aphids are on all the leaves of our two mature oak trees (English oaks, I believe), and then the...
Knowledgebase
Aphids / honeydew on oak trees #869462
Asked May 21, 2024, 1:34 PM EDT
I read the Extension page about aphids. Every summer, aphids are on all the leaves of our two mature oak trees (English oaks, I believe), and then the sticky honeydew substance coats everything in our yards. So far, the aphids seem to only live on the oaks and not attack the rest of our garden. These trees are much too tall to spray with water (or wipe off the leaves). Is there anything I can do to try to prevent or control the aphid infestation (or reduce the honeydew problem)? Would it be helpful for me to buy and release ladybugs now that the honeydew is starting to appear this year?
Thank you for your assistance.
Benton County Oregon
Expert Response
Spraying water seems to be the most effective solution. If there are any lower branches you can spray with a hard stream of water then that can target some of the population and potentially help.
You could release ladybugs into the canopy of the tree, but there is no guarantee they will stay in your trees. There is some anecdotal recommendations that if there is a large enough population of aphids they will be more likely to stay because the food source is high. And if you have honeydew production then the population is likely high. Also, you can release them in the evening requiring them to eat before leaving and potential stay because they know there is food available. If you decide to go the ladybug route please buy native ladybugs.
You could release ladybugs into the canopy of the tree, but there is no guarantee they will stay in your trees. There is some anecdotal recommendations that if there is a large enough population of aphids they will be more likely to stay because the food source is high. And if you have honeydew production then the population is likely high. Also, you can release them in the evening requiring them to eat before leaving and potential stay because they know there is food available. If you decide to go the ladybug route please buy native ladybugs.
