Elm Tree

[Darin]

I am asking this for a friend as I did not know the answer. In the picture below, I didn't know if you knew what type of insect did this and how to prevent it. It is a chinese elm and he uses the trees for shade. Although the shade isn't plentiful as many (most of the leaves) are eaten. We don't see any insects or we could find the culprit. Let me know if any of you can help. Thanks.

 

[Kneejerk Bombas]

I see two different types of injury to the leaves. The little tiny holes that don't go through all the way through could be caused by by Elm Leaf Miners. They seldom reach populations where control is needed, but I have seen them get pretty bad.
The holes that are chewed all the way through could be Japanese Beetles, if you have them in your area. This is the time of year when you would expect to see the damage from them.
If the leaves shown are typical of those damaged, I would not be at all concerned. It looks like less than 5 or 10% of the leaf surface is gone. If it is much worse, then we need to explore whether or not this is really a Chinese Elm, and not a Siberian Elm, or something else.
I mention this because Siberian Elms will actually hold up better if they lose a good percentage of foliage each year to insects. This slows growth and lightens the canopy load. This tree is so weak wooded, that it is just asking for trouble to try to achieve a lush full canopy. Michael A. Dirr calls this "One of, if not, the world's worst trees."

 

[John Paul Sanborn]

Being that the leaves are not all that glossy, and that it is in Colorado, I would lean heavilly towards Siberian elm on that. Many us Chinese for the coloquial, because Siberian has such a bad rep.

Siberian is U. pumila
Chinese is U. parvifolia, below is a leaf pic

Also notcie how the leaf is fatter towards the tip then your sample.

So that all said, if the aesthetic damage is so bad your buddy want to spray, then I would agree with Mike in finding the damaging pest so proper timing can be done next year.

A systemic like Orthene works well, but it is an organophosphate (read neurotoxin) so many object to that. With soaps and oils you need to know ehn the bug is active so you can cover it best.

 

[Pgtree]

Since its in the Denver area, its probably a siberian elm.

There are two very common insects that attack virtually every sibo in town they are elm leaf beeltes and leaf miners. Your pics dont show leaf miner damage but do show elm leaf beetle damage.

the problem is completely aestetic. There are several hatchings per summer, so to try to control it plan on having it sprayed at least once. squirrels are a much bigger problem with the sibos, there are on their preffered food list.

bottom line is if you have a sibo in denver, you have elm leaf beetles, leaf miners, and squirrels, period. its best to learn to live with them.