What is this on our aspen trees

Question: We are Colorado Natives, but have not seen these spots, like water spots, on our aspen trees. The branches droop, and do not look good.
Thank you.

responder: An Ask Extension Expert Replied August 06, 2024, 6:19 PM EDT
response: Deni,  Thank you for your question and picture.  Can you please submit a picture of the entire tree. Also, a  picture of the dropping branches.  Please answer these additional questions; Are all of the leaves affected? What area of El Paso County do you line in?   Kindly,  Kerry P El Paso County Colorado Master Gardener

responder: The Question Asker Replied August 07, 2024, 4:07 PM EDT
response: Thank you Kerry for getting back with me. We have several aspen trees, the ones I’m showing you get water, they are on drippers. It’s very strange. Some 4” trunk size trees, we have lost. Just makes us sick. Here are a few pictures. Thank you much again. We live in Black Forest, off meridian and Woodlake, 10 miles north of falcon. Thank you Deni Offord  Sent from my iPad On Aug 6, 2024, at 4:19 PM, Ask Extension <<personal data hidden>> wrote:   ﻿

responder: An Ask Extension Expert Replied August 08, 2024, 1:36 PM EDT
response: Hello Deni, We have been  reviewing your question from 8/5  regarding the spots on your aspen leaves. I believe you were talking with Keri P on this. Another master gardener, Trudi, found the link below which we believe is the issue. It is damage from the Aspen Leaf Blotch Miner Moth. Although the damage is visible, it isn't much threat to the life of the tree. The article below will tell you more about it. Thank you for contacting the Master Gardener help desk and please contact us again if you need anything else. Happy Gardening! Jasper B apprentice and Adrian H Master Gardener  https://somethingscrawlinginmyhair.com/2011/01/08/aspen-leaf-blotch-miner-moth/

responder: The Question Asker Replied August 15, 2024, 4:38 PM EDT
response: Hi. We want to thank you all for the information. The leaves are all dropping off, even our big trees. Is there a systemic control of what can we do to stop this, especially in the big trees?   We thank you very, very, much again for all your help. I looked all over for pictures of those leaves, but couldn’t find it. Just need to stop the damage.    Thank you much     Deni Offord     <personal data hidden>Sent from my iPad On Aug 8, 2024, at 11:36 AM, Ask Extension wrote:﻿

responder: An Ask Extension Expert Replied August 15, 2024, 5:42 PM EDT
response: Hi Deni,  This is Kerry, again. Great question.  Below is what [W.S. Cranshaw, Colorado State University Extension entomologist and professor, bioagricultural sciences and pest management; D.A. Leatherman, entomologist, Colorado State Forest Service; and J.R. Feucht, former Extension landscape plants specialist and professor, horticulture. 3/96. Revised 7/14.] Colorado State University suggests.  Management of Leafminers of Trees and Shrubs Few, if any, leafminers pose any significant threat to the health of trees or shrubs. Injuries are cosmetic and treatment decisions are based on plant appearance. Furthermore most leafminers have numerous natural enemies that normally well regulate their populations. Outbreaks, if they occur, are usually very short-lived. However, exceptions to this can occur among the non-native species that are not as well regulated by natural enemies in areas such as Colorado where they have been recently introduced. Examples of non-native leafminers are those found on elm (elm leafminer, European elm flea weevil), birch (birch leafminer), and the tentiform leafminers of apple. If controls are attempted with insecticides there are two approaches to consider. The first involves sprays applied to leaves that are timed to coincide with periods when egg laying occurs – usually shortly after leaves have expanded in spring. Persisting contact insecticides can be used for this purpose, such as the various pyrethroids that currently predominate for control of insects that chew on leaves (permethrin, bifenthrin, lambda-cyhalothrin, cyfluthrin, deltamethrin), None of these will move systemically in plants so active larvae within mines will not be affected. Sprays of systemic neonicotinoid insecticides (imidacloprid, dinotefuran) can provide some control of these stages among leafminers that are beetles (Coleoptera) or sawflies (Hymenoptera). Neonicotinoids tend to be poor in control of caterpillars, the larval stage of moths (Lepidoptera). Alternately, neonicotinoid insecticides can be applied to the soil for root uptake. Imidacloprid (Merit, various generics) is widely available for this application both through most nursery outlets and by commercial applicators. Dinotefuran (Safari) is presently only available through commercial applicators. Hope this helps. Let us know if you have any additional questions.  Kindly,  Kerry P.  Colorado Master Gardener, El Paso County