Knowledgebase

Black Locust Tree infestation #757509

Asked June 21, 2021, 2:36 PM EDT

Good afternoon. My name is Josh and I am contacting you today in an attempt to identify what appears to be an infestation that has occurred across all the branch ends and new growth on one of the Locust trees on my property. If you could help me out with identification and treatment options I would greatly appreciate it. If you need any more info please just let me know. Thank you,

Calvert County Maryland

Expert Response

Hello Josh,

These are aphids (and the white flecks are their shed skins), and while often numerous, their feeding rarely causes serious problems for plants, especially trees. Many beneficial insects prey on aphids, and they should catch-up to the infestation soon to reduce their numbers. We see at least one aphid "mummy" in the picture, so some are already beginning to work. (See the photo of an aphid mummy under Management - Biological on this page.)

Spraying, even with an organic pesticide, risks killing the beneficial insects along with the aphids. Since the impacts of aphid feeding are minimal to negligible for the locust, we don't recommend any treatment with pesticides. If the tree is young enough to reach, you can try blasting off aphid colonies with a strong jet of water, but it's otherwise not necessary.

Miri

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