Yated Neeman has a letter from Rabbi Moshe Wye on a little-discussed halachic issue for Sukkot: Insects falling from your s’chach into your food. [See note below.] The Hebrew text appears on the Jerusalem Kosher News blog. I summarized the most important points below:
“Permanent” s’chach, usually made of bamboo and stored from year to year, is the most likely to have bugs. S’chach of all types, whether old or new, needs to be checked. Rabbi Wye advises spreading out a white surface such as paper or a tablecloth, holding the branches at an angle, and banging them on the ground. The white surface should then be examined for bugs.
If you see small insects, spray the s’chach with insecticide. A few hours later, shake the s’chach to disperse the dead insects. A brush or vacuum cleaner can help remove them.
Lyctine beetles, dark brown and about three millimeters long, often infest dry s’chach. They chew narrow tunnels under the thin skin of the bamboo stalks, and you can see round holes on the outside of the stalks. If you find these, use a professional exterminator and ask for a guarantee. If the infestation is large, don’t use the s’chach at all.
To store s’chach from year to year, spray with insecticide, let dry completely, and wrap in a sealed waterproof plastic bag. Check again after opening.
Note: During the week-long festival of Sukkot (Tabernacles) beginning October 2, observant Jews eat and often sleep in a temporary booth, called a sukkah. The roof is made of branches or other vegetation, known as s’chach. Aside from hygienic issues, bugs, whether dead or alive, are not kosher.
Don’t Bite the Bugs: How to Avoid Insect Infestation in Food (at CookingManager.Com)