Earlier this year, I was able to get some bindweed gall mites, under USDA permit, from a researcher who was investigating bindweed mites. (I'd send them these photos directly, but they have since retired.) 

My understanding is that these mites can take years to have an appreciable effect on a bindweed infestation. Just a few months after introducing them though, I'm already seeing significant plant injuries. However, the severity and types of injury looks to be far too substantial and fast to be caused by the mites.

Photos: Some vines are missing most of their leaves, but tend to look healthier closer to the base of the stem. Some have holes in the leaves. Some have small spots. Some have mottling across much of each leaf. (also attached here is a mostly-healthy vine, for reference)  
Region: Northeast US.

I have noticed a very small number of small caterpillars on the leaves. But I have yet to see one do so much as take a single nibble, or even move at all. Holes in leaves and completely-missing leaves is consistent with the feeding habits of some caterpillars. But then there's the mottling on some leaves. I don't know what would cause that.

No herbicides or sprays or anything like that has been used here.   
  
So with the researcher retired, I guess I'm posting this here mostly to see if anyone has any thoughts on what I'm seeing here, if this is something that's actually of interest for controlling bindweed, or if it'll turn out to be "Yeah this happens sometimes, not noteworthy."

  
(Also, semi-related: Colorado residents can get on a waitlist to get some bindweed gall mites: [https://ag.colorado.gov/conservation/biocontrol/field-bindweed](https://ag.colorado.gov/conservation/biocontrol/field-bindweed) )

Something is attacking my invasive bindweed, but I'm not sure what.