One must be extremely careful to avoid even the slightest possibility of eating something non-kosher, for through a prohibited food the body grows in a forbidden manner and the person will not be able to grasp the Path of Life — to fear and love the great and awesome Hashem — or to serve Him perfectly. Therefore one must take care to instruct his family to check their food thoroughly for the presence of worms or other infestation. One should make sure to not eat any fruit that is prone to infestation unless it was cut and examined first. During the summer, especially, one must be vigilant and make sure that no mosquitoes, fleas or other small bugs fell into the food.
One must be thoroughly knowledgeable in the laws [of Kashrus, including the laws] of wine and food handled by gentiles and of the status of meat that was left unattended without supervision. How good and proper it is to act with abstention and flee as far as possible even from things that are permissible so that you can avoid even the smallest exposure to something prohibited. And, One who gaurds his mouth and his tongue guards his soul from troubles (Mishlei 21:23).