Insect eating crabapple tree leaves

Question: Hello-I have an insect eating the leaves off my crabapple tree. I’m wondering what I can use to treat this?

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied July 22, 2024, 4:10 PM EDT
response: Hello Debra I don’t see any insects in the photos. He first one came out very blurry, but looks like a fungus on the leaf.  Could you attempt to get a clear shot of the insects? If you could capture some in a jar, put the lid on, and freeze them; then dump them out on a plain piece of cardboard, that would allow you to photograph them.  The leaves on the ground could be from a caterpillar or beetle feeding on the tree. As long as the tree is healthy up to 25-30 percent of leaves can be lost with no ill effects.

responder: The Question Asker Replied July 22, 2024, 6:04 PM EDT
response: Hello-I am attaching some better pictures. I have no proof there are insects, I just assumed. Perhaps it is a fungus. It is mostly at the top of the tree, and the bottom leaves appear healthy. So in the first picture I’m showing what the leaves look like that are attached to the tree. Middle picture my view of the tree from the ground. Third picture the fallen leaves. Any help you could give would be appreciated!  Thank you, Deb Burkhard  Sent from my iPhone On Jul 22, 2024, at 4:10 PM, Ask Extension <<personal data hidden>> wrote:   ﻿

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied July 22, 2024, 7:49 PM EDT
response: Hi, Unfortunately the camera focused on the paper towel and not the leaves. If you could, please retake that picture using smooth flat plain cardboard, cardstock, index card, typing paper, etc.  It is hard to tell if this was fungal or if it was damage from an insect without a very clear shot of the leaf surfaces. Some leaves turned face down, and some turned face up would be best. Sorry to be such a bother!

responder: The Question Asker Replied July 22, 2024, 7:56 PM EDT
response: Let me know if this is better or if you need another try.  Thank you very much! Deb  Sent from my iPhone On Jul 22, 2024, at 7:49 PM, Ask Extension <<personal data hidden>> wrote:   ﻿

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied July 22, 2024, 9:54 PM EDT
response: Thank you, the last one is good. I am referring to an expert, and we will let you know if we can tell you more.

responder: An Ask Extension Expert Replied July 23, 2024, 1:07 PM EDT
response: This damage does look like the work of insects. Determining which insects would require some more detective work on your part. Some of the damage looks like it may have happened weeks ago and the insects responsible may have already moved on to finish their life-cycle elsewhere. There are many different insects that can produce this type of damage to crab apple leaves. The fact that you have not seen any on the tree, would indicate that they feed at night and/or that they are one of those insects that is very skittish and flies or jumps off of the leaf before you can catch them in the act. The good news is that this type of damage at the extent I see in the photos, is well within the tolerable range for a mature crab apple tree. I suspect that the insect responsible will finish their life cycle and move on soon, if they haven't already. You could try inspecting the tree at night with a flashlight, to see if there is anything feeding on it nocturnally.