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Insect galls on tree leaves #913831

Asked August 13, 2025, 1:42 AM EDT

I am curious about what insect is creating these galls. I believe that it is an elm (Ulmus americana) sapling because it is growing five feet away from my house. An elderly elm tree on my property died a few years ago, and my yard has many elm saplings perpetuating its memory. Thank you for your information.

Ionia County Michigan

Expert Response

I believe that the galls on your elm tree are caused by elm sack gall aphid. Here is an article from The Ohio State University about two common aphids that cause galls on elm trees. 

Galls are typically harmless and do not need to be treated. They might be considered unsightly, but they do not do lasting damage to the tree. 

Lindsey K. Kerr, MS, MHP  Replied August 13, 2025, 3:00 PM EDT
Thank you for your information about the elm sack galls.
I've always desired to be able to identify properly my pests.

Now I need to deal with the ground-dwelling yellow jacket wasps that stop me from weeding/mowing my yards.
My city public safety officer has requested that I deal with the tall weeds ("over six inches tall"), but the critters attacked me twice with their stinging defenders. 
Isn't nature just wonderful with its territorial fauna.
I know that the first frost will eliminate them, but that's a lotta time yet.
I purchased a bag of Diatomaceous earth to dust, but then our 90oF temperatures intervened. 

Bye for now, and thank you again.
From: ask=<personal data hidden> on behalf of Ask Extension
Sent: Wednesday, August 13, 2025 7:00 PM
To: thcaadoc
Subject: Re: Insect galls on tree leaves (#0183747)
 
The Question Asker Replied August 13, 2025, 8:10 PM EDT

Here is an article from MSU Extension "Getting rid of wasp nests". Scroll down for information about "Removing yellow jacket ground nests".

The main thing is to be safe. 


Lindsey K. Kerr, MS, MHP  Replied August 14, 2025, 9:41 AM EDT

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