Fee Fi Fo Fum Who is Eating Our Grape Leaves?

We are seeing a few of our vines with this type of damage where only the leaves have been munched on. We ruled out deer and we have looked on the plant to see if we can find the culprit, but no such luck. The damage is localized and only a few of the adjacent plants are showing this type of problem.
What this reminds me of is the damage that we suffered last year from the beautiful but voracious Eumorpha pandorus. You would think with the bright orange coloration that we would be able to spot this leaf muncher pretty readily, but it has proven to be quite evasive.
The plants that have had their leaves eaten are responding by growing their lateral shoots so it still looks rather green and now, somewhat bushier.
Here is a close-up from last year of the type of damage that this caterpillar can do.