Certain types of Schach have been found to harbor various insects, the Kashrus Bedikas Tolaim said. “As it has been observed, those insects tend to drop from the Schach, and are liable to fall into food below. But with the proper precautions, we can protect ourselves and not cause the mitzvas Sukkah, to be a ‘mitzvah haba’ah be’aveirah’ as the Aruch L’ner cautions.
See the attached pages for instructions on how to rid your Schach of these insects.
Click here for English
Click here for Yiddish.
The product that is mentioned in the instructions is very toxic! Please see these two websites and there are others. One of them mentions that the product itself has instructions that read that adutls and children should not enter area until the spray has dried (I have no idea who IS supposed to spray if not adults!). Certainly, pregnant women and children should not be near this product under any circumstances.
http://www.raidkillsbugs.com/en-us/products/raid-house-and-garden-bug-killer-formula-7
http://www.doh.wa.gov/Portals/1/Documents/4300/Pesticide-BugBomb-EPARecommendations.pdf
Placing the light in the corner of your succa and not over the table helps too.