What's eating my nannyberry?

[Jerry-B-WI]

Planted 10 nannyberry plants this spring and was watering them the other day when my son saw one that where the leader had died. He broke off the dead section and an ant rushed up the stem and plucked this grub out of the stem. What type of grub would it be?

I understand the aphids that are being farmed but don't get what the grub is.

They all got a good spray of bifenthrin.

 

[H20fwler]

Has it rained since you sprayed? Looks like some kind of caterpillar, I think I can see one on the top of the main lead?

 

[Bowsnbucks]

Also looks like aphids on the stems of those upper leaves. Sevin spray will kill both caterpillar and aphids.