I don't know, but I've noticed the curled leaves on the Texas Ash and some other things as well. What time of day did you see them? I found some worms (dark ones) out in the evening.

The two most annoying things on ash trees here are leaf-footed bugs and a kind of sawfly larva...don't remember the exact species of sawfly, but the larva (worm) are whitish to light greenish. I had them recently on both Texas Ash and Arizona Ash. Butterflies? Seen any that look like Tiger Swallowtails? I am worried about the two species of tigers swallowtails we have in Texas. I've usually seen quite a few by now and fear they may have been wiped out in the state last year by drought and wildfires. I miss them!

No, the butterflies were not Tiger Swallowtails. They were mostly bright orange with some black on the tips of their wings.

The tiny white bug was aphids. I had no ideas aphids attacked any kind of tree. I called an aborist to come out, then went to Google whatever I could find. Before the arborist got here, I found an article about aphids on Texas Ash trees and butterflies flocking to the trees. Eviently the aphids leaves some kind of sweet "honeydew," which is what was attracting the butterflies. The article even had pictures.

When the arborist came out and looked at the tree, I asked him if he thought they were aphids. He stated that they indeed were aphids and that the butterflies liked the "honeydew" the aphids left on the trees. The aphids destroy the brand new growth on trees, but evidently will not kill the tree - just makes it look ugly and not grow new growth due to the destruction the aphids cause.

Had to spray for aphids. Then decided to look at the tree in the back and found aphids on them, too, so sprayed. I will just continue to watch for aphids.

I too have a beautifully growing Texas Ash shading my back southern-facing porch from the brutal Texas summer sun. I love butterflies and have studied them all my life and was quite surprised to see flocks of Hackberry butterflies and Red Admiral butterflies all over the ends of the branches feeding all day, since ash is not on the diet of either of those species. Quite a sight, but when I saw the curled up leaves I suspected something was attacking the tree. I assumed the butterflies were sucking up sap from the leaves, but y'all's posts have helped me - THANKS!!

Now to return the favor, since we know these are aphids, I have the perfect solution...LADYBUGS. These cute little insects are quite the predators and their favorite meal is aphids. I'm heading out today to a local nursery that sells them in a little mesh bag. All you have to do is put them in the refrigerator, where they go into a kind of "cryogenic" sleep until you are ready for to release them. Just take them out and they will come right back to life. I'm going to start releasing handfuls near my ash tree today.