Glen, we have the same problem here in the States. I don't think Dutchman's Pipevine is considered a noxious weed or invasive yet, but the the Pipevine Swallowtails lay their eggs on it, only to die. However, in the far south, like Florida and Texas, the Polydamas Swallowtail can and does use it. I went with the native Aristolochia tomentosa (Wooly Pipevine) so I could enjoy both butterflies! I have a theory regarding the varying toxicity of pipevines and whether certain caterpillars have evolved to handle certain amounts of the aristolochic acids contained in them.
FYI, the Pipevine ST is pretty much a North American butterfly. But the Polydamas ST is mostly Central and South American, along with the various Caribbean islands and extreme deep south of the U.S. Since Polydmas is used to the tropical, South American pipevines, it can eat them with no problem. But since most people in the U.S. will only ever see the Pipevine Swallowtail, it's really important to pick a species native to where you live. I'm glad our friends Down Under are doing the same!
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