I’ve been trying for years to entice Pipevine butterflies to lay their eggs on my gigantic Pipevine which crawls up the side of the house. I’ve only found larvae once in seven years. It was so discouraging, I was very close to ripping out the Pipevine and putting in a different plant. I’m glad I didn’t since I’ve finally figured out what they seem to want. The don’t want a gigantic plant with older leaves, they want a tender young shoot just coming out of the ground. I’ve dug these out in years past – now I know better.
Sherry, another butterfly devotee, gave me this advice: “In my case, I’ve got so many cats that few of the leaves on my vines get a chance to age – the cats keep them pruned and making new growth. I fertilize mine once or twice a year to keep plenty of new growth coming. In years past my vines have grown vigorously without cats chewing the leaves, and I cut them back deliberately to encourage new growth. Pipevine swallowtail females almost never lay eggs on old, tough leaves, so if I were you, I’d prune and fertilize them.”
Pipevine Sprouts
Video Below:
Butterfly Gardening 
Same with monarch. They prefer the young plants to lay on first.