I researched butterfly larvae for an elementary school project. I didn't end up doing it, but they sell a kit and then you order how many larvae you want. 1 larvae unit = 4 caterpillars (for example). Can also do the same for ladybugs. Do a search on the internet for bug habitats/kits and you'll find a wide variety of sizes, prices, etc. The prices were reasonable and included the caterpillars, food, habitat for them to spin their cocoons, etc. I'm glad you found the pesticide now instead of wondering for another 7 years why butterflies never came. I'm including a link I found for swallowtails below. Good luck!

Here is a link that might be useful: Swallowtail Caterpillars for Sale

First things first, make sure you let your lawn service know to stop spraying pesticides and herbicides. They aren't good for humans. Second, buy some parsley that hasn't been sprayed and plant it in pots. I use bronze fennel, too. That's a good host plant, too.

I'm posting where to buy butterflies. There's a couple of farms in NY.

Here is a link that might be useful: NY Butterfly Farms

I don't allow them to spray in my backyard, but they sprayed in the morning, and I figured out when I came home, because of the little white flags, and the strong chemical smell. Thank you so much for the links, but I'm having trouble finding any places that sell Eastern Blacks, without having to pay $200 for a release box! I have bought monarch eggs from butterfliesetc.com, but they unfortunately don't have Black Swallowtails. If any of you have ever bought EBS eggs/chrysalids online, please give me the link. Overall, thank you so much for providing me with all of the links here.