I bought a hop tree this year and just today (Sept 9th) I found these ugly things on my very small tree. They ate so much of the tree I hope it will come back next year. I think I have five of the worms. I put them in a jar and am now waiting for the the metamorphosis to happen. They were partially on there way anyway. I use to do the same to the tomato worms. It really is so cool to watch it all happen right before your eyes. I can't wait for the butterflies. to appear. Thanks for all the info from all of you above . Everything from each of you has been very interesting to say the least.

I am so sorry! According to the messages I've read these worms don't hurt my tree. I killed six of the ugliest worms I'be ever seen yesterday. They were eating all the leaves. Then I mixed a solution of dawn dish washing liquid and water and sprayed my tree till it was dripping. I didn't know I was killing beautiful butterflies. The worm is sooooo ugly and destructive. What is more, I don't know if the dawn solution does any good. Help!

Please do not kill the caterpillars. Pretty please?? You can hose down the tree to wash the soap off.

These are not worms; they are caterpillars. Butterflies lay their eggs on host plants so when the eggs hatch the caterpillars will have food to eat. The caterpillars will develop through several instar and when they are full sized, they transform into a chrysalis. The chrysalis will then turn into a butterfly.

Hop trees are host plants for the Giant Swallowtail Butterfly along with Rue, Orange Trees, Prickly Ash and citrus. They do not kill or hurt your tree.