If you have room in your yard for a smaller tree, Hop Tree/Wafer Ash, Ptelea trifoliata, is a great choice. For the past ten years I’ve noticed that Giant Swallowtails use this tree as a host plant.
What I just noticed yesterday was that a Tiger Swallowtail was also laying eggs on this tree.
I also have a Tulip tree in my yard, which is also a host plant for Tigers, so I was surprised to see the Tiger use my Hop Tree as a host plant. I have found other internet resources indicating that Hop Tree is a host plant for Tigers.
This tree takes vigorous pruning without complaining so don’t be bashful if it gets a bit to large to your liking. I’ve also found out that there are male and female varieties of this tree. One tree has hundreds of seeds, while the other never has a single seed.
If you want some seeds later in the year, let me know. The seeds germinate easily with cold stratification.
Butterfly Gardening 
I got a hop vine and am hoping it will help attract the butterflies to lay eggs on also.
l don’t get many butterflies in my yard. I do have black swallowtail and spicebush cats but wish i could increase. I have bought as many larvae plants as my garden will handle that I can think of, any suggestions? My garden is two years old.
Thanks for the tip! I’m going to look for one on my next trip to the nurseries!
It’s very early in the season – don’t panic. If you plant them they will come. I also give plants to my neighbors to increase the number of plants in our neighborhood.
It’s really neat to watch Question Marks and Commas lay eggs – they lay them on top of each other! I wonder why – seems like the early emergers would eat the other eggs. I have seen a Monarch cat eat another egg.
I would like to get some of the Hop Tree seeds if you have them available later this year. Will you please post when you have them available?
Tom,
What are the tall red flower or maybe really dark orange flowering in your yard?
I’ve got some right now – send a SASE to
Tom – Hop Tree Seeds
9016 Robyn Rd
St. Louis, MO 63126
I just noticed this – they could be Maltese Cross.
I’ve cut them down to the ground now and they will bloom again later.
are you sure that it is a host plant to tiger swallowtails
I personally have never seen Tiger Swallowtails use this as a host plant, but then I have a tulip poplar tree which I know they like.Other sites have this listed as a possible host plant.I use the Ptelea primarily for Giant Swallowtails which lay eggs on mine every year.