Keeping Bugs in Check Insect Infestation Revisited

Published Fall 2011

1. Introduction

Over the past number of years, there has been much discussion regarding insect infestation and the procedures used to check fruits and vegetables. Many guides have been published, many lectures and demonstrations have been given, L’Hagdil Torah Ul’hadira. However, infestation can and does change over time,1 so it is worthwhile to step back from time to time and review the facts as well as the procedures used.

The Biblical prohibitionof eating insects is extremely severe. Depending upon the type of insect eaten, a person can violate as many as six Biblical prohibitions2 for each insect ingested. Furthermore, the negative spiritual effect that eating shratzim, insects, can have on a person is particularly detrimental.3
Insect infestation is not a recent phenomenon. Since the times of chaza”l4until today, poskim have been dealing with this issue.5The bottom line is that the fact remains that many species of produce have infestation issues and it is not possible to simply ignore the issue and pretend it doesn’t exist.6 While the USDA is aware of the existence of insects in produce, their guidelines are hardly a consideration from a halacha standpoint.7Unquestionably, if we are to enjoy our vegetables, we have to find effective ways to control or address infestation.
As we know, the Torah was “not given to angels,”8and we are not expected to be able to avoid eating something which we can’t see. In truth, the insects we are discussing are all considered by halacha to be visible to the naked eye, Nireh L’Einayim. This means that they are able to be seen without the aid of any special magnification or tools. A jeweler’s loupe or light box may be used to make checking easier, quicker, and more efficient, but they are not used to find insects that otherwise would not be visible due to their size.9The fact that bugs can hide in the crevices of a leaf or inside a broccoli floret does NOT make them invisible to the naked eye.10
Insect inspection is a skill that requires proper training and decent vision, as well as a lot of practice and patience. What at first glance may appear to be a piece of dirt, may actually be an insect. All Star-K mashgichim who inspect produce are personally trained, tested and specially certified to check for infestation. It is worthwhile to point out that as in all areas of Torah, a personal lesson is preferred. Glossy color guides are excellent resources for reference and further knowledge but should not replace a personal lesson.
A complete discussion of this topic is beyond the scope of this article. However, we will provide a general overview of what needs to be accomplished from a halacha perspective and explore the practical application primarily in an industrial setting11

  1. Halacha Overview

There are three categories defined by halacha regarding what needs to be checked: 1) Rov – something that is infested a majority of the time (over 50%); 2) Miyut HaMatzui -something that contains a significant percentage of infestation, although less than a rov; 3) Miyut ShEino Matzui ­-something that is infested only rarely or infrequently.
How one defines what constitutes a Miyut HaMatzui or ShEino Matzui is a lengthy discussion amongst the poskim.12 The generally accepted guideline13 is to follow the opinion of the Mishkinos Yaakov,14 that Miyut HaMatzui is anything infested between 10-50% of the time and Eino Matzui is anything which is infested less than 10% of the time.
How are these percentages determined? Do we look at each species or each harvest or each field or each serving, etc.? Rav Moshe Heinemann, shlit”a, paskens15that the percentages are determined by serving or portion size.16 This means that if one insect is found in ten inspected portions, one will have a 10% infestation rate. This is determined after one washes the produce.17
It is also important to have an understanding of the mechanics of the requirement to check for infestation, chiyuv bedika. Each individual has an obligation to check food which may be infested before he is permitted to eat it. If the produce passes inspection, it may be eaten; if it fails, it may not. There is no pre-existing prohibition, issur, on any one particular lot of lettuce; each lot is evaluated on its own merits. In classic Yeshiva terminology, there is no prohibition on the cheftza (lettuce), rather an obligation on the gavra (to check and/or remove any insects from his food).
The requirement for checking fruits or vegetables with an established rov of infestation is M’diorayso.18 This means that the Torah requires inspection of fruits and vegetables that are infested a majority of the time (a rov). The requirement for inspecting vegetables whose infestation is less prevalent, Miyut HaMatzui, is Midirabanan.19 These requirements may be fulfilled by either checking each item and removing the insects20 or subjecting the produce to a process that effectively removes the insects.21
Having said this, with the increasing popularity of pre-washed bagged salads, the time needed for preparing salads has dramatically decreased. The question however, begs to be asked. How can produce be effectively cleaned to a degree that avoids leaf by leaf inspection? How can massive amounts of vegetables be processed and verified as “free from further inspection”?
Before we address these questions, we need to familiarize ourselves with the ‘facts on the ground’ regarding crop dynamics.

  1. Fact Check

Fact number one: Infestation can and does vary greatly by region, country, and continent. Produce that may be very infested in Eretz Yisroel or other countries may not be as infested in North America.22 All of the information presented in this article applies only to produce found in North American markets.
Fact number two: Crops can vary from one section of a field to another. This includes variances in taste, color and ripeness, as well as infestation. The reason for this is the various factors which contribute to the finished product, which include but are not limited to sun, water, wind, and soil conditions. These factors can vary for each area of the field. An area where there is more moisture, less wind, and warmer weather is a more inviting environment for insects. Due to these factors, farmers will generally harvest each section of the field separately23 and assign unique lot numbers which  follow that section all the way through production.24
IV. Factory Settings
In large production facilities, head lettuces such as romaine or iceberg lettuce and cabbage, arrive daily on large pallets, each with its own unique lot number. The heads are cored and topped, and the outer leaves removed, either in the field or the washing facility. The lettuce is then sized and sent into a wash system, which can use either a long flume or triple wash systems. The lettuce is vigorously agitated and washed in 36oF chlorinated (or other anti-bacterial chemical) water, and is placed on a vibrating screen to remove any residual water. It then enters into a large spinner, which dries the lettuce more thoroughly so it will retain shelf life. From there it is fed into a hopper, where it is packed into bags.
Star-K requires that every single lot of romaine lettuce be checked by a mashgiach before it can be certified.25 A large sample is taken from each lot after it is washed and is checked using a lightbox. If no insects are found in the sample, that particular lot can be certified.26  If even one insect is found, the entire lot is rejected and will not be certified. Since each lot is uniform and undergoes the same washing process, the test sample serves as a clear indication of the cleanliness of that particular lot.
When a lot of romaine passes, the Star-K symbol is added to the date code. When there is no Star-K symbol on a product, it is an indication that the lot failed inspection. Consumers should be aware that some produce companies attach stickers to their product, implying that it has been kosher certified. At times, these stickered bags do not bear the Star-K symbol by the date code. The absence of the Star-K symbol by the date code means that that particular lot failed inspection or was never checked. Other stickers caution the consumer in Hebrew and state that inspection is required before rinsing the lettuce. Consumers are urged to look for a reputable symbol to be sure that no further checking is necessary.
The above mentioned washing system is used exclusively for fresh romaine lettuce, and is not designed for other leafy vegetables such as spinach, broccoli, or herbs. The only available options for these products (fresh or frozen), if you don’t want to check them yourself, are those varities grown in greenhouses and/or certified with reliable kosher certification.

  1. Strawberries

Strawberries are more difficult to check than lettuce. The prevalent culprits are mites and baby thrips or nymphs (also known as thrips larvae). These thrips are small and white (but still very visible), resembling a strawberry seed but merely a quarter of the size. They tend to hide either around the base of the top green area of the strawberry, or in the crevices next to the seeds. It can take a considerable amount of time to check even one strawberry. Additionally, wet strawberries are even more difficult to check since water droplets can easily hide these insects. Fortunately, strawberry insects are significantly easier to remove, and if the prescribed washing method27 is followed correctly no checking is necessary.
Industrially produced strawberries pose an unusual challenge. Strawberries are a very sensitive fruit, and many companies are afraid to subject them to an aggressive washing procedure since it may damage the fruit and reduce the quality and shelf life of the finished product. For most companies (and the USDA), a quick rinse or mist spray using an edible anti-bacterial solution is enough. From a kashrus perspective however, this is far from adequate. At a recent inspection at two different strawberry facilities, a 40-50% infestation rate was found after the washing process was completed.
Star-K requires that strawberry companies use a washing process that agitates and soaks the strawberries in a strong (food grade) solution.28 The solution is tested until acceptable water/chemical proportions are found, and then the solution is subsequently metered in to the wash using a computer. This ensures a consistently insect-free product, without the need to check every lot.29 Star-K recommends that consumers only purchase retail packaged strawberries bearing the hechsher of a reliable certification that has adequately addressed this issue. Consumers can enjoy fresh strawberries by using the same washing method employed in an industrial setting. The Star-K recommends vigorously agitating the strawberries in at least two tablespoons of liquid detergent per gallon of water, letting them soak for approximately one minute and then rinsing them off thoroughly before eating.30  No further checking is required.

  1. Checking on Shabbos

There is a Biblical prohibition of Borer, selecting, on Shabbos. This involves removing any unwanted item from a mixture of other items. This would also include washing produce that is subject to infestation.31  If there is no requirement to check this item,32 one is permitted to wash it as long as the intent is solely for cleanliness.33 One may however, check produce and use it if it is found to be insect-free.34 If an insect is found, it may not be removed;35 however, one may remove the insect together with a piece of the fruit.36

There is much written about the tremendous rewards and holiness that we merit by avoiding forbidden foods.37 May our heightened awareness of these issues bring much Kedusha into our lives, and may we all merit a Ksiva Vechasima Tova.

1.וכן ע’ ש”ך יו”ד סי’ פ”ד ס”ק כ”ב

2. There are three types of שרצים . 1) שרץ המים which is four לאווין ; 2) שרץ הארץ which is five לאווין ; 3) שרץ העוף which is six לאווין . The איסורים are listed in ויקרא פרק י”א and דברים פרק י”ד .

3.ע’ שו”ת ודברת בם (פסקים של הגר”ד פיינשטיין שליט”א) סימן ר”י. וכן יעוין בספר בדיקת המזון כהלכה מאת הרב משה ויא שליט”א שער ראשון פרק א’ שמאריך בזה

4.ע’ חולין ס”ז ע”ב, סוטה ג’ ע”ב

5.יעוין בפרי חדש סי’ פ”ד ס”ק כ”ב. וע”ע בספר בדיקת המזון כהלכה פרק ג’

6.ע’ שו”ת ודברת בם הנ”ל

7. For example, the USDA Food Defect Level Handbook allows up to 60 aphids, thrips, or mites per 100 grams of frozen broccoli. A standard 32 oz bag of frozen broccoli is over 900 grams.

8.ברכות דף כ”ה ע”ב

9. ע’ אגרות משה יו”ד ח”ד סימן ב’

10.ע’ חכמת אדם כלל ל”ח סי’ ח’, ערוה”ש סי’ פ”ד סעיף ל”ו

11. For a more comprehensive guide, which includes instructions for home and other non-industrial use, please visit the STAR-K website (here) to view or download the STAR-K Guide to Checking for Insect Infestation or visit

12. ע’ שו”ת הריב”ש סימן קצ”א, שו”ת שבט הלוי ח”ד סימן פ”א, שו”ת ודברת בם סי’ ר”ז

13. פסק של הג”ר שלמה זלמן אוירבאך זצ”ל

14. תשובות סימן י”ז

15. יעוין בתשו’ חת”ס יו”ד סי’ ע”ז

16. This is still difficult to determine definitively, as lettuce can vary greatly by season. It is worthwhile, however, to quote the words of the משכנות יעקב וז”ל כל דבר שנראה לעינים שהוא מצוי תדיר זה שמו אשר יקראו לו מיעוטא דשכיח עכ”ל.

17. יעוין באג”מ או”ח ח”א סי’ קכ”ה שדרך אכילה היא לרחוץ את החסא קודם שאוכלה

18. ע’ ש”ך יו”ד סימן פ”ד ס”ק ל”ה

19. ע’ פמ”ג שפ”ד סי’ פ”ד ס”ק כ”ח

20.  רמ”א סי’ פ”ד סעיף ח’

21. יעוין בשו”ע סי’ פ”ד סעיף י’

22. One example of this is strawberries. In Eretz Yisroel, all the leading experts require peeling or soaking strawberries for numerous extended periods of time. In North America, all that is required is soaking one time in a strong solution and then rinsing. See Star-K guide for more detailed instructions.

23. For quality purposes

24. This is a USDA requirement for traceability, in case a recall becomes necessary.

25. The washing process is not effective enough to be able to create any sort of chazaka for cleaning romaine lettuce properly on a consistent basis; therefore, every lot is checked. For iceberg lettuce and cabbage however, the industrial washing processes (at least in STAR-K certified facilities) has consistently been proven to effectively clean the lettuce completely. Iceberg lettuce and cabbage are closed heads (as opposed to romaine, which is open) and, therefore, they are less prone to infestation. Additionally, the leaves are much stiffer and smoother and insects tend to wash off much more easily than on romaine. Therefore, hashgocho temidis is not needed for iceberg lettuce or cabbage.

26. There are two reasons for this. First, Rav Aharon Kotler, zt”l, paskened that since there is always reason to believe that this lot may be from the majority that is not infested, one may take three servings and check them. If they are clean, we may consider the rest of this lot not infested and it need not be checked. See טוב טעם ודעת מהד’ קמא סי’ קכ”ג and ברכי יוסף יו”ד סי’ רצ”א and דרכי תשובה יו”ד סי’ פ”ד אות קי”ט-קכ”א . Second, even without using a chazaka, if the sample would be divided into ten portions and one insect is found then the rest of the lot must be considered Matzui, so too, if no insects are found then the rest of the lot may be considered Eino Matzui.

27. See STAR-K Guide to Checking for Insect Infestation.

28. This system is only used for frozen strawberries where the companies are less concerned about damaging the fruit since they will anyways be frozen. An alternate process that one company uses is a system of brushes that scrub each berry, thereby effectively removing all insects.

29. If one is going to puree the strawberries, there are those who are lenient due to the fact that any insects will be crushed and batul/nullified in the rest of the puree. Each person should consult their own rabbinic authority for guidance on relying on this lchatchila.

30. As an extra assurance, it is preferable to remove the top green area.

31. שו”ע או”ח סי’ שי”ט סעיף ח’, שמירת שבת כהלכתה פרק ג’ אות י”ח

32. For instance, if it is something known to be אינו מצוי .

33. אגרות משה או”ח ח”א סי’ קכ”ה

34. שמירת שבת כהלכתה שם אות ל”ו

35. שמירת שבת כהלכתה שם אות י”ח

36. משנה ברורה סימן שי”ט ס”ק ס”א ושם

37. ע’ יומא ל”ט ע”א, חכמת אדם סי’ ל”ח ס”ק כ’, ערוה”ש סי’ פ”ד ס”ק ס”ד, העמק דבר עה”פ והייתם קדושים (ויקרא י”א, מ”ד)