According to the Torah it is strictly forbidden to eat any swarming creatures, such as insects, flies, worms or their eggs.  (Source: Leviticus Ch.XI, 20-23).  Whenever preparing fruit or vegetables therefore one must examine them very carefully for any sign of infestation. 

It is customary to soak lettuce and other problematic vegetables in a bowl of water with a little salt, which helps loosen the grip of insects, before rinsing and inspecting.  All fruit and vegetable should be thoroughly washed before use.  See “General Guidelines for checking of insects” in the directory.