Hello all, hope the growing season is being kind to you all!

I have discovered a budworm infestation in my petunias that I started from seed myself, and planted into pots in the front of our house. He looks exactly like the picture I have attached. I saw the worms all over in the pots when I was inspecting the plants after discovering that blooms were being eaten, and drowned them in Sevin soon as I did. As you probably know, that did not kill them. I googled them, figured out what they were and that they are difficult to kill with insecticides, and the best way is to just pick them off. So I started trying to pick them off, but I keep missing some, it takes forever to go through all of my petunias, and I keep coming back to find them everywhere. I grew 6 packets of petunia seeds and didn't lose a single plant over the winter, so there's a LOT. Now I'm even having nightmares about these darned worms, like 5 foot budworms coming out of my plants..seriously. I need to get rid of them. I read that BT works, but want to be sure. I am assuming my local nursery will carry this, planning to head up there today, but I've never used it. Has anyone used BT on budworms? If you've had problems with budworms what worked? I don't want to keep wasting money on insecticides only to find I just have to keep picking the buggers off.... Thanks!