Ken, I think you need to find new places to shop! I'm always a bit suspicious if I don't see caterpillars on host plants. Some of them are grown in greenhouses so I understand that part. But so many of the big box stores spray them so I don't tend to buy them from there unless I'm desperate. And even then I quarantine them for a few weeks and spray them down a lot. The place I mentioned, Hollie's, also has several host plants planted (not for sale, obviously) throughout their property so they usually have caterpillars on the plants they sell. It always makes me feel better knowing I'm buying a host plant that isn't going to kill my caterpillars. Which reminds me, I need to contact them and see if they have any rue yet. They said it usually comes in with their vegetable shipment.
Another great source around here are the USF Botanical Garden plant sales. It's mostly made up of the various clubs in the area: Bromeliad Guild, Orchid Society, Native Plant Society, Begonia Society, African Violet and Gesneriad Society, etc. So you not only don't have to worry about pesticides and such for the most part, but you get educated people who know the plants and they often sell them for very reasonable prices because they're just raising money for the club, not trying to make a profit. There are also businesses and for-profit nurseries there, but you can definitely find some great deals and unusual plants. The Native Plant Society has been a great source of hard to find host plants for my butterflies. And I don't have to pay an arm and a leg!
The tough part is being quick to the booths! They let members in a half hour early and of course, I'm a member. It's so funny standing in line, listening to other people talk about what they're there for. Because everyone is competition! I usually go for the bromeliads first. Mom comes with me, and she's in charge of the garden cart. So one year we're standing in line, going over strategy, and I say, "Okay Mom, you're in charge of the cart, I'm going to run." And the lady in line ahead of us just busted out laughing. I was like, "Hey, you have to plan these things!" How else do I get the best bromeliads? And the Bromeliad Guild knows me well enough that the guy always points out the more unusual or rare things to me which is super nice of him. And by the time Mom catches up with me (she knows where I'm headed) I've usually picked out a few plants and we start loading them in the cart. It's also fun trying to make your way back out with a giant bromeliad sticking out of the front. I try to tell people, "Get out of the way! These things are spiky and hurt!" But some people don't listen very well. One time I bought a Quesnelia quesneliana and the inflorescence was sticking out of the front of the cart. And we got stopped by so many people asking what it was and where we got it. I told them, but I didn't say it was the only one they had!
They might find something else they like at the Bromeliad Guild booth, right?