Although eating insects is strictly forbidden by the Torah, we find this concern often overlooked. Following is an example of some products that may contain bugs or worms.
It is important to realize that we are prohibited from the Torah (Vayikra XI) to eat Sheratzim. This issue includes many types of insects. Therefore, a bowl of salad which may look kosher, could have more non-kosher ingredients (bugs) and prohibitions than a cheeseburger at a local fast food restaurant. Although Reb Moshe Feinstein zt”l states that it is not mandatory at this time to check vegetables for bugs, he was refering to a time when DDT (a strong pesticide) was widely used on most crops. This pesticide, when used, served to temporarily eliminate the vast majority of insects from vegetables. Unfortunately, due to various agricultural modifications, the insects are back! In the United States, the insecticide DDT is now officially and legally outlawed. Now, often over half a dozen species can be found on one head of lettuce. Usually, something as small as an insect would be “batel” (anulled) in a large volume of permissible food. In the case of insects, however, this is not the case. The reason is that we have a rule which states that a complete creature cannot become nullified. Therefore, a worm on the bottom of a tequilla bottle does not become nullified by the liquid. However, if a person cooked soup and found a fly floating in it later, the fly should be removed and the soup will now be permissible. If there were three or more insects in the food, we have to assume that it was infested with insects and must be sifted, strained etc. If there are only parts of insects, they are considered nullified in sixty. However, whenever possible, a person must try to remove the insect parts as well. This is the reason why in Israel many people who have found insecdt parts in their flour always sift it. In most countries, flour is pre-sifted. Microscopic insect parts do not concern us halachically. The following FDA list shows the maximum givernment tolerance when it comes to insects found in food, and illustrates clearly how we often are not aware of what we are eating. There is a company in Israel that grows their produce in sand, which has proved effective in avoiding insect infestation even in leafy vegetable. In the U.S., pre-checked lettuce, cabbage etc. are being marketed under a reliable hecher. The chart on page 195 will explain how to check for bugs in most cases.
Chitin, a chemical derived from the shells of lobsters, crabs, and crayfish (and potentially from insects) has been approved for use in cereals by the Japanese as a source of fiber and calcium. This has not affected the produce in the U.S. at this time.