Question
I live near Pittsburgh PA..  Do you know of an effective organic way to protect zuchini plants from what I've been told is the larva of a moth that bores into the base of the plant and causes the plant to wilt and die?  I've seen the dischrge of the insects outside of the tunnels they've bored.

Answer
Vince, the larvae you described is the larvae of the squash borer.  The moth lays the egg in the stem and the squash worm then matures and does its damage.  It is always fatal to the plant.

The only organic insecticide that kills the larvae before they do the damage is BT, short for Bacillus thuringiensis.  This product is more commonly sold under the brand names Dipel or MVP. It is a dust that is non-toxic to humans and beneficials but highly effective against caterpillars and hornworms.  You can purchase this product through on-line catalogs such as Gardens Alive or locally at many garden centers.

Depending on how far it has traveled within the stem, it is not always easy to locate them.  Unfortunately, once the borer does its damage, there is little chance for the plant to survive.

There are a couple of preventive measures you can take in the future.  The first is to cover the plants with reemay while they are just seedlings. Reemay is a lightweight, spun-woven fabric that lets in air, water, and sunshine, but keeps out insects and pests.  It is commonly sold at garden centers as floating row covers.  Just be sure to remove the covering once the plant begins to flower to enable access by bees for pollination.

The second option is to wrap your stem with aluminum foil.  Many gardeners do this routinely with much success.  I would personally recommend covering the plants when young, and then wrapping the stem once the plant begins blooming.

Attached is a website that will give you additional information on the squash borer.

http://www.ag.ohio-state.edu/~ohioline/hyg-fact/2000/2153.html

I hope this helps.  Please write again if I can ever be of assistance.

Regards,

Mike