Problems with growing zucchini - part 3

Ever notice your beautiful zucchini plants suddenly wilt in what seems like overnight. If so, a squash vine borer is probably to blame. Unfortunately, the damage is already done by the time you notice the first signs of the plant beginning to wilt. The infested plants usually die very quickly (24-48 hours after I first notice the plants looking weak).

Squash vine borer larvae

The squash vine borer has a cream colored body with a brown head. It overwinters just below the soil surface and emerges in the spring as a moth. The moth looks more like a wasp with an orangish-red body and black wings. The moth lays individual small brown eggs on leaf stalks and vines of zucchini plants. Once hatched, the larva immediately bores into the stem where it feeds before exiting the stem to pupate in the soil. If the plant dies before the borer has completed its life cycle, the larva can migrate to a neighboring plant and resume feeding there.

Frass

The burrowing larvae destroy the internal tissue of the zucchini plant causing the whole plant to die. You will likely notice something that looks like wet sawdust around the base of the plant. This is excrement from the squash vine borer called frass and it is the telltale sign that a squash vine borer has been enjoying dinner at the expense of the zucchini plant. 

Squash vine borers are difficult to control, so the key to squash vine borer management is controlling the borers before they enter the stem. Promptly pull and destroy any plants killed by squash vine borers.

In my experience, the squash vine borer is the worst insect that can invade my garden as it does the most damage before it is even detected.