Is checking for bugs halachically required?

Question

Various methods of checking for bugs in produce, i.e., lettuce, are officially recommended by kashrus agencies and other halachic professionals. However, is use of one/any of these methods--or even a formal check--halachically required? Or is the halachic requirement simply that one not eat bugs?

MOTIVE: For certain mitzvot, such as taharas hamishpacha and Pesach preparation, checks are halachically required, and--at least for taharas hamishpacha--one must perform them in a certain way. (Moreover, for taharas hamishpacha, the check is sufficient to establish the condition halachically; here, I ask if the same is true with regards to checking for bugs.) I am wondering if the same is true for food. Is a check [of a certain kind] halachically necessary?

IMPLICATIONS:

• Could a self-designed method of checking be halachically acceptable? What level of reliability would it need to have in order to be so?

• From whom can one learn a method for checking for bugs? Could one adopt the method suggested by, say, someone with a lower kashrus standard, but who still keeps kosher?

• Could no method (that is, no checking) be acceptable if one knew the lettuce to be free of bugs?

Answer 1

The Shulchan Arukh's stipulation that only insects visible to the naked eye are prohibited (84:36) carries the suggestion that checking foods visually is halachically necessary.

This document brings several sources that the checking process itself ("bedikas hamazon" or "bedikas toalim") is indeed halachically required:

What frequency level of infestation obligates a person to check a particular fruit or vegetable? If it is a “miut ha’matzui”, a frequent minority, the vegetable must be checked. What percentage is considered a “miut ha’matzui”? This is the subject of dispute between many authorities. Rav Moshe Vayeh in his sefer Bedikas HaMazon K’Halacha (Part II 3:2 footnote 3) quotes the Responsa Rivash 191 that it must occur with a frequency of close to 50%. The Mishkinos Yaakov (YD 17) says that there is an obligation to check for insects even if they occur ten percent of the time. The Shevet HaLevi (IV:81) and others explain that the b’dika is not based on a specific percentage; rather there is an obligation to check any item which is frequently infested by insects. Even if the particular item has a low percentage of infestation, if we see that it occurs regularly, there is an obligation for bedika. Rav Shlomo Z. Auerbach rules like the opinion of the Mishkinos Yaakov and that the number 10% is determined by the item in question. For example, if one of ten (10) heads of lettuce contains one or more insects, it requires bedika. NOTE: If an item which does not require inspection was, nevertheless, found to contain three or more insects, it must be fully inspected. If inspection is not possible the food must be discarded (Shulchan Aruch YD 84:9).

[...]

According to HaGaon Rav Shlomo Zalman Auerbach ZT’L, produce which cannot be checked [e.g. broccoli and cauliflower florets, frozen spinach, canned asparagus] may be used without inspection in the following manner: Break apart florets, agitate and soak in water for ten minutes, pour off water, cook until soft. Puree finely in a blender or food processor. Use as desired (e.g. in kugels or quiche).

This text seems to imply that checking is both a halachic requirement under certain circumstances and optional under others.

Kof-K does not, however, supply any halachic sources for the instructions they give for checking, and I do not remember seeing such citations in any other guide. So there is still the question of who decides what checking procedures are acceptable, how, and whether this decision is based on halacha or mere practicality.