Insects and Diseases of Pawpaw Trees

Insect Pests
In its native habitat the Pawpaw has few pests of any importance. The pests that do attack the Pawpaw plant are uniquely adapted to do so, since all parts of the plant except the wood contain potent pesticides. These are the insect pests which we see here in the Ozarks:

This is *Omphalocera munroei, the Asimina webworm moth*. The caterpillar feeds on Pawpaw leaves, buds and twigs in the late Summer and Fall, and can devastate young trees. It can be controlled by dusting with Bacillus thuringensis, ( BT ), while the larvae are feeding.
		Here are the Adult Moth and Pupa. These two photos: Copyright © 2007 Jeff Hollenbeck


These are the leaf roller larvae.	This is what they do! Nasty!

	Another "pest" is Eurytides marcellus, the Zebra Swallowtail Butterfly, whose larvae feed exclusively on young Pawpaw foliage, but never in great numbers. The adult butterfly is of such great beauty that Pawpaw trees are sometimes planted to attract them. Sometimes we have Zebra chrysalises for sale. Please email if interested. (See also our *Butterfly Garden* page.)
Zebra Swallowtail Butterfly adult, on a Pawpaw leaf in our nursery.

The Larva.	The Chrysalis.


These are "Stinging Rose Caterpillars", Parasa indetermina (Family Limacodidae). We've only seen it once on Pawpaw leaves. They are also found on apple, cottonwood, dogwood, hickory, oak, redbud, sycamore and rose bushes, usually in August.

Does Climate Change Cause New Insect Problems?
In the late summer of 2010, when it was was unusually hot and dry here, we first observed Japanese Beetles and Striped and Spotted Cucumber Beetles nibbling on the leaves of the Pawpaw trees in our nursery. We did not observe them on the wild or orchard Pawpaw trees nearby. This may have been because our nursery trees were well watered and fertilized, in contrast with most other plants in the area, thus making them relatively attractive to these insects which do not ordinarily feed on Pawpaw leaves. We will see if this happens again in 2011, and post our observations and pictures here.

Diseases
Small brown spots sometimes appear on Pawpaw leaves in humid conditions, such as might occur with young trees in poorly ventilated greenhouses, in tubular tree shelters, or if they are surrounded by dense weeds. This is caused by fungi, is usually not serious, and can be alleviated by improved air circulation.

There is an disease of Pawpaw trees that has been reported in the Pacific Northwest, in which the trees have bark lesions, which show blue streaking in the cambium when cut open. The trees often die. The cause is not known. We have not seen this disease here.