You will have to replace it each time it gets wet. Do you know what the bugs were that you are trying to control? Have you seen them this year yet?

Diatomaceous earth....call it D.E.

I can't think of any pests of zucchini that DE would prevent.

Diatomaceous Earth has been listed as a control for slugs and snails and many other crawling insects that might eat many plants when dusted on the soil. When dusten into the tunnels the Squash Vine Borer makes it may be effective, as reported by many organic growers.

To be effective the DE must be dry, so you will need to reapply each time the garden has been wet.

kimmq is kimmsr

I'm pretty cautious with DE. DE kills soft bodied insects and such, some of which are beneficial.