Tim Wong has worked long and hard on his Pipevine Swallowtails. Not only raising and releasing the butterflies, but also raising awareness about their habitat and hostplants. Which is wonderful. I just worry that gardeners are going to be disappointed when they put pipevine (Aristolochia californica) in their garden and it doesn't bring the butterfly immediately.
I know some people have fabulous luck when planting pipevine and have females laying eggs in their yard almost immediately. But other people (such as myself) have pipevine for years with little luck.
I suspect that the lucky ones live near an established colony. I don't exactly know how close the new pipevine would have to be to the old. But I am guessing it would need to be within a quarter mile. I am about a mile from a colony on the UC Berkeley Campus. And about half a mile from a colony in flatlands Berkeley. But I have only had eggs one year in the approximately 20 years I have had pipevine in my yard. :-(
In addition, according to the literature, a colony needs at least a football field of pipevine. The colonies I am aware of have much less than that. But they do have more than would ordinarily be found in one backyard.
So, yes! Please plant more pipevine! But also, encourage your neighbors to plant pipevine. And if you can provide a corridor of backyard pipevine extending from an established colony to your property, you are more likely to have success with butterfly visitors.
The Pipevine Swallowtail is a big beautiful butterfly and a big beautiful caterpillar. I support all efforts to increase the population so we can all enjoy seeing more of it.
The pipevine plant is not particularly showy. But the weird flowers and delicate vine are a nice addition to native gardens. Like most vines, it likes heavy shade for the roots and dappled shade on the leaves. Mine is very happy growing up through a rhododendron. I am hoping to see eggs on it in he spring.