caterpiller infestation

Asked August 6, 2015, 12:17 PM EDT

Hi, I happened to glance at a young Catalpa tree in my yard and noticed that something was eating the leaves away. Upon close inspection, I see these gross but attractive lime green and black stripped caterpillar like creatures all over the tree along with smaller ones and white eggs. The biggest ones were the size of your pinky. They were only on one tree that I could see. I became very alarmed because I have a beautiful 60-70 year old Catalpa over my picnic table nearby. I picked them off one by one and places them in a jar with air. What are they? Should I destroy them? i also have a 75 year old sugar maple nearby that is sick....meaning the branches are dying on one side and no leaves appeared this spring. Help! Thank you! Regards, Craig Bartolozzi 412-691-7942 or 724-326-4539 I live in Dunlevy Boro in Washington County- 15432

Washington County Pennsylvania entomology caterpillars catalpa horticulture

1 Response

Based on your description, I think that the caterpillars are the larval stage of the catalpa sphinx moth. Here's an excellent article with photos to help you identify the caterpillars: http://www.ag.auburn.edu/enpl/bulletins/catalpasphinx/catalpasphinx.htm

If there are many caterpillars on your young tree, they may defoliate it. This will not kill the tree, as it should leaf out again, but it is very unsightly. To control the "catalpa worms," the following steps can reduce damage to trees:

  1. Search the foliage on small trees for egg masses and tips of branches for larvae, then prune and destroy infested foliage.

  2. Chemical control may be required on larger trees. Certain formulations of carbaryl (Sevin), malathion, or acephate may be used. If the tree is very large, you may need to hire a certified arborist to treat the tree.

  3. If practical, in the fall, till the ground thoroughly in the immediate vicinity of tree trunk to destroy over-wintering pupae.

There is a small native wasp which predates the caterpillars. It lays its eggs on the caterpillar which then hatch and eat the caterpillar. If you see "Catalpa worms" covered with eggs, do not destroy them. Another interesting fact is that the "catalpa worms" are highly prized as bait by fishermen. Many catalpa trees were planted by fishermen to attract the catalpa sphinx moths.

As for your sugar maple, it may be infected with verticilium wilt. Would you be able to send a photograph to help me make a diagnosis?