Hello Christie,

There are several reasons for leaf damage like this: Wind, hail, or insects. Oakland County got hit by at least a couple severe storm complexes that may have caused physical damage to the leaves. However, the “circular holes” on the edges of the leaves are definitely indicative of an insect dining.

Any insect with chewing mouthparts could have caused this damage – Caterpillars, grasshoppers, earwigs, weevils, beetles and even Leaf cutter bees. The summer of 2023 was favorable for abundant insects because last winter’s cold was not severe enough to kill off the over-wintering stage and we didn’t have a late spring hard freeze to kill the early emerging insects.

Since the damage is seen on several different species, it is likely not a pest that targets a specific type of plant. The one that concerns me is the rhododendron. There is a weevil that attacks rhododendrons that can be problematic. Please see this article for more information on the black vine weevil: https://www.canr.msu.edu/news/black_vine_weevil_damage_to_rhododendrons

As much as you may disagree, for the most part, the damage is cosmetic more than destructive. There is nothing more that can by done this year, because any future generation of insect is already in its winter resting stage.

Next spring/summer, monitor your plants very closely (once a week or more frequently) and as soon as you see damage, check daily for the actual culprit. Look at different times of the day and even use a flashlight to check at night. Check the tops of leaves, underside of leaves and even the ground. Remember you will need to look closely. A lot of insects naturally blend in with the foliage as a defense mechanism. If you see the damage spreading, keep looking carefully to find the cause. Once you find the actual insect, we can help you with remediation techniques. Take detailed, close-up, well-lit photos of any insect you find. These will be invaluable when you write back for further suggestions.

Here are some resources you can study about Insects that feed on leaves:

Caterpillars:

https://extension.umn.edu/yard-and-garden-insects/caterpillars-ornamental-plants

Beetles:

https://extension.unh.edu/resource/beetles-ornamental-plants-fact-sheet

Leaf Cutter Bees:

https://bygl.osu.edu/node/1705

Grasshoppers:

https://bygl.osu.edu/node/411

Earwigs:

https://extension.usu.edu/pests/uppdl/files/factsheet/earwig-orn.pdf