I have the same problem off ants herding aphids on a apple tree I have in a pot. And all I can say is is there any end to the uses for duct tape! I just wrapped the tape over on it self to make it double sided then wrapped it around the trunk! Then shook the tree to remove the ants then they can't get back on within 24 hours I had captured ants and aphids alike and no ants on the tree! Change the tape every few days and there's still no ants on the Tree one month on!
