Thrips On Strawberries

Note: Not intended at all to be pesak halacha.


So this was linked to on Areivim -- new issues regarding a procedure of cleaning strawberries. Click on the picture to see it bigger, so as to read it.

Basically, they found infested California strawberries from four different brands. After soaking and stirring the strawberries in soap water and then rinsing it under a strong stream of running water, a few thrips remained. Another method (to kill the thrips and cause them to lose their grip) produced the same results - a few thrips left.

This lab concluded that one should use one of the other gadol-certified methods - approximately (read for more details):
1) peel the strawberries and then wash them under running water.
2) Cut off the green leaves and a thin layer of fruit from the top, cut off any deep crack or hole, soak for three minutes in soap water, and rinse and rub every strawberry under running water.
3) The aforementioned procedure of soaking, rinsing, rubbing done 3 times (but I guess not cutting off the green top), after which they may be eaten completely ground, cooked, or baked.

The image also contains answers to whether something is miut sheaino matzui, etc.

I grew up with a milder form of procedure 2 (but perhaps this was before extreme infestation) -- I would cut off the green leaves and a thin layer of fruit, where the bugs might hide or run from, and then wash the entire bowl of strawberries. (But would not soak for three minutes in soap water, etc.) Perhaps nishtaneh hatevah and we have more thrips in current infestations, or perhaps I've been eating thrips all along.

For example, in this news report from 2006, about thrip attacks on strawberries:

Dale Secher is President of the Wisconsin Berry Growers Association but also owns a farm that's been hit with a wave of Eastern Flower Thrips. For him, this is a quality control issue. The berries look different, taste fine but are not up to his standards.

UW Bug expert Phil Pellitteri has only been studying this for a week but he's heard of infestations from Appleton to Racine to Madison . The small bugs attack the plant's flowers. When the berries ripen, Pellitteri says they turn bronze in color, are smaller and seedier but taste fine. Pellitteri says there's nothing for consumers to worry about.

Eastern Flower Thrips are nothing new. They're found mostly in greenhouse plants but seeing the tiny bugs in such waves in a widespread area is different even for bug expert such as Pellitteri. He says he's never seen anything like this in his twenty-eight years of running the UW-Madison's diagnostic lab.

Thus, it may well be that these infestations at such levels are indeed something new, and nishtaneh hateva -- the metzius of the prevalence of this bug has changed.

However, to the average Jew, this approach may well come off as crazy. It is one thing to say that due to increased infestations this year, it is impossible to prepare strawberries in a normal way, so one should not buy strawberries at present. Such has probably been declared in the past about other produce, and this seems like a normal point. Perhaps because of the "gimme" culture, or a desire to find an halachic solution to this issue, they find ways that would be successful in removing all thrips so as to permit the fruit.

But to someone not used to it, telling him that the only way to eat strawberries is to peel them -- he'll look at you like you are trying to impose a new, crazy chumra, over the normal way to eat strawberries. He's never prepared strawberries like this in the past! And it seems like this would not only take away from the beauty (and thus appeal) of the strawberry, but also cut away the tastiest part.

The same goes for soaking in soap water. We wash dishes with soap, but food?? Wouldn't soaking food in soap cause it to absorb a soapy taste? Wouldn't is take away from the strawberry's taste? Even if it would not, the procedure makes it somewhat unappealing -- even if you don't taste the soap, you imagine that there is soap absorbed into the flesh of the fruit.

But if such is the only way to ensure its kashrut, so be it. It could use some better PR and presentation, though, in terms of the first thing I said, for those who are not ready to soak their fruit in soap water.

Now on to my ruminations.

I wonder whether this is true for every strawberry. For matzah that they were unsure if it was leavened, there were signs -- cracks in the surface like the antennae of grasshoppers. So too, perhaps, there are signs that a particular strawberry has been infested.

To cite from the aforementioned news article:

For him, this is a quality control issue. The berries look different, taste fine but are not up to his standards.
...
The small bugs attack the plant's flowers. When the berries ripen, Pellitteri says they turn bronze in color, are smaller and seedier but taste fine.

Thus, if we are speaking of the same thrips (we seem to be), a strawberry attacked by thrips in its development will be smaller and seedier, and perhaps bronze-ish in color.

When this kosher lab inspected these boxes of strawberries for infestation, were these signs present? I don't know -- perhaps they later spread from strawberry to strawberry after harvesting, but perhaps not.

If so, if there is a much stronger chance of infestation on such strawberries as opposed to others, perhaps we can take strawberries which are less likely to be infested and use a lesser procedure on them, which would then bring us to miut sheaino matzui. (See the image above for a brief discussion about miut sheaino matzui.) With "a more definitive method,"they found one thrip remained amongst 300 strawberries. But choosing among strawberries for signs of infestation may reduce that even more, and maybe then it would not be a miut hamatzui.

There are other signs of thrip infestation:
Flower thrips (in strawberries):

Thrips invade strawberry fields from blooming citrus, clover and wild flowers. Although thrips are not strong fliers, winds aid their movement into flowering strawberry fields. Thrips rasp the portions of the strawberry flower that develop into fruit, causing it to develop poorly. Damaged green fruits may become bronze or grayish and very fine shallow cracks may develop in their surfaces. As these fruits ripen, they remain dull in appearance. Thrips damage can easily be mistaken for damage caused by powdery mildew or by spray burn. This insect occurs on every farm in every year and may require control measures.

Furthermore, we have this form of thrip damage:

The presence of dark colored spots of excreta adjacent to light colored feeding zones are some typical signs of thrips damage. They may be collected by a variety of means. For example, species found on vegetation may be collected by sweeping.

One should think that it is possible to distinguish thrip-damaged strawberries, and treat them specifically.

Of course, I am no entomologist, and don't know anything about the metzius of this other than what I read on the Internet. Those who are paskening may well know more about the specifics of the issue, and of the halachot and how they apply.

I also wonder -- thrips are presumably nothing new, so what did generations past do? We don't hear of Chazal soaking their strawberries in soap water. To an extent, this is parallel to the question of copepods (though there are indeed nishtaneh hateva aspects to copepods in terms of the way we collect and treat our water.)

However, the prophet Amos enabled people to eat infested sycamore figs. Amos 7:14:

יד וַיַּעַן עָמוֹס, וַיֹּאמֶר אֶל-אֲמַצְיָה, לֹא-נָבִיא אָנֹכִי, וְלֹא בֶן-נָבִיא אָנֹכִי: כִּי-בוֹקֵר אָנֹכִי, וּבוֹלֵס שִׁקְמִים.

14 Then answered Amos, and said to Amaziah: 'I was no prophet, neither was I a prophet's son; but I was a herdman, and a dresser of sycamore-trees;

The dresser of sycamore trees, is has been determined, is one who cuts sycamore figs so that they ripen early. The sycamore wasp laid her eggs inside these figs and if they were permitted to develop, the fruits would taste bad and would only be fit for animals. By ripening early, the figs tasted good, even though there were developing wasps/eggs inside.

And even if you say this is Biblical practice recorded in Navi, from which we cannot extrapolate halacha (even though is is gilui milsa beAlma), Chazal also held that certain types of tolaim were permitted when developing inside produce. See Chullin 67b. All that is forbidden is the sheretz which is shoretz al haAretz, and a brayta says that that excludes sheratim inside various produce. Now, Shmuel teaches that certain sheratzim in certain produce is forbidden. And they explain/reinterpret the brayta according to him, that it refers to ones which became wormy (hitlia) after it was separated from the ground, but if when connected to the ground, the fruit is considered as the ground and so it was shoretz on the ground. (But see my previous post about whether we should really follow forced "explanations" of braytot.) Rav Pappa in interpreting Rav Huna makes a statement about what Shmuel would have to then hold, which is taken as evidence by some (e.g. Rav Achai Gaon, Rif, Ran) that we hold like Shmuel. But there are other braytot (which are also "answerable" to Shmuel) which seem to suggest a straightforward reading of the first brayta, and against Shmuel, so some (like Rabbenu Tam) hold against Shmuel.

Developing tolaim, in the mindset of Chazal, was probably a stage of rot leading to spontaneous generation of the bugs. Thrips occasionally reproduce via parthenogenesis (asexual reproduction) but mostly from eggs laid either on the surface of the fruit or else in slits the mother thrip cuts into the fruit, depending on the species. To cite Wikipedia:

To survive the winter temperatures most thrips species over-winter as either adults or as pupae under ground litter. A typical flower thrips generation time will be from 7 to 22 days depending on the temperature. The eggs are about 0.2 mm long and reniform (kidney shaped), and may take on average 3 days to hatch. Thrips have 2 larval stages then go through a prepupal and a pupae stage, with the adults taking 1 to 4 days to reach sexual maturity. In the two suborders, the females of the Suborder Terebrantia are equipped with an ovipositor which they use to cut slits into plant tissue into which they insert their eggs, one per slit, while females of the Suborder Tubulifera lack an ovipositor and lay their eggs singly or in small groups on the outside surface of plants.

We will deal with the most problematic aspects first. Mature, adult flying thrips are obviously the most problematic of them all, because besides whatever issues we may have of them when on the fruit, we saw that they also fly (assisted by or carried by the wind) from nearby flower fields on to the strawberries. And Rav Ashi asks whether if it separated from the fruit into the air (and then was caught), whether that is considered forbidden (because of being shoretz) on the ground. And the gemara leaves this as a teku, such that the question is unresoloved, which means in case of Biblical prohibitions, we rule leniently. However, I believe that we say that Biblically, safek deOrayta lekula, and that safek deOrayta lechumra is Rabbinic. If so, we may be dealing from here on, in terms of these, as a Rabbinic prohibition rather than Biblical, and combined with other factors, might solve the problem. (Of course, if it took flight, there is a possibility -- I'm not sure how remote -- that in the middle they landed and swarmed on the ground.)

However, are the thrips on the strawberries really these thrips which have taken flight? According to this page on Avocado thrips (I am assuming strawberry thrips are similar), thrips have the following lifespan:

Table 1. Biology of avocado thrips on Hass avocado at three different temperatures.

Biological Attribute	Temperature 20oC (67oF)	Temperature 25oC (77oF)	Temperature 30oC (86oF)
Average adult life span	14 days	10 days	3 days
No. eggs laid per female	31 eggs	20 eggs	not determined
Egg to adult development time	27 days	20 days	16 days
No. days for eggs to hatch	14 days	11 days	9 days
Proportion of Females	0.69	0.62	0.58
Net Reproductive Rate	15	5	not determined
Population Doubling Time	7 days	10 days	not determined

I assume it is fairly hot right now in California, so 3 days should be the lifespan. But even assuming a 14 day lifespan, those original thrips which flew from the nearby clover and wildflower fields should be dead. The new thrips were hatched from eggs laid on the surface of, or slightly beneath the surface of, the fruit.

The live thrips we have on our fruits may well be ones that were hatched after the fruit was harvested, in which case perhaps even according to Shmuel they would be permitted. And otherwise they were hatched while the fruit was attached to the ground, in which case it is a dispute amongst Geonim and Rishonim whether they are forbidden or permitted.

However, presumably that dispute was about worms and such in the fruit, not on the surface of it. Rav Ashi asks about toalim that crawled upon {or to} the roof {/surface} of the fruit, and the question is left unresolved, as a teku. So once again, safek deOrayta lechumra.

Do we know, though, that these thrips crawled {were shoretz} on the surface of the fruit. Part of the problem of washing the strawberries is that the thrips stick themselves into the fruit and do not let go, as they feed on the fruit. If so, are they really moving over the surface of the fruit after hatching? This is a question about the metzius, and I am not sure of the answer. We should determine it. Regardless, although they are on the surface of the fruit, I don't think they leave the surface of the fruit to crawl on the ground and then return.

Perhaps, then, we can find a way to permit the strawberries. These adult thrips are small (1 mm or less, hatching from eggs which are .2 mm (=200 microns). They are hard to see without the help of a magnifying glass and are not moving around such that they look like they may be part of the fruit. We might be able to bring in that the Torah was not given to malachei haShares, to angels, but rather to humans. And that in previous generations they ate strawberries without soaking them for long periods in soap, then squishing them up. This might not be sufficient in and of itself, since now we are aware of the issue and they are visible with the right checking, etc. But then perhaps we can combine a safek or a sefek sefeika, such as perhaps these are permitted based on the brayta, if these thrips developed after the fruit was detached, or (if we don't hold like Shmuel), when they were attached. And perhaps the thrips did not swarm on the surface of the fruit, etc. And if the fruit does not show immediate signs of infestation, and looking at it quickly we do not know that there are thrips on it, and we then take steps which are partially effective in removing thrips -- cutting off the leafy top and a bit of flesh under it and rinsing it well, perhaps we would be able to say that we do not know that there is a miut there, and even if there, it might be permitted to eat it anyway, or else only Rabbinically forbidden.

Once again, I should stress that I did not look sufficiently well into the metzius of the matter or into the halachic aspects of the matter. This was just recording my initial impressions of the matter. And do not act based on what I say here. Consult your local Orthodox Rabbi.