For the past few days, the Gemara has been discussing the mitzvah of kisui ha’dam, the requirement to cover a slaughtered animal’s spilled blood with earth. A mishnah on today’s daf explores whether this practice is required if the animal turns out to be unfit for consumption:
In the case of one who slaughters and the animal is discovered to be a treifa … Rabbi Meir deems one obligated to cover its blood, and the rabbis deem one exempt.
While Rabbi Meir’s minority opinion is that the blood of an unfit animal should still be covered, the majority opinion exempts a person from this obligation. The rabbis also exempt a person who causes a disqualifying injury to the animal during the slaughter itself:
One who slaughters an animal or bird, and it became a carcass by his hand, and one who stabs the animal or bird, and one who tears loose the windpipe and the gullet — these are all exempt from covering the blood.
The rabbis rule that if a person kills an animal or bird in a manner that is not kosher slaughter, they don’t have to cover its blood. It’s understandable that mistakes in slaughter occur. But why would a person inflict such an injury on purpose — for instance, stabbing the animal? Surely, that would be a waste of otherwise edible meat! One surprising answer is shared on today’s daf by way of an anecdote:
Moths infested the flax of Rabbi Hiyya. He came before Rabbi Yehuda HaNasi to ask how to get rid of the moths. Rabbi Yehuda HaNasi said to him: Take a bird and slaughter it over the tub of water in which the flax was soaked, as the moths will smell the blood and leave the flax.
How could Rabbi Hiyya do this? But isn’t it taught in a beraita: One who slaughters a bird or an undomesticated animal, and does so only because he needs the blood, is nevertheless obligated to cover the blood (and may not use it for any other purpose)?
In Colorado, where I live, we are beset each year in the late spring by an inundation of miller moths, so called both because they have a flour-like dusting on their wings and because they can burrow inside grain. (Ask me how I know. Eww.) One of the popular ways to get rid of miller moths is to turn on a bright light bulb over a sink or counter, then place a dish of soapy water directly underneath, causing the moths who become attracted to the light to singe their wings and plummet to their soapy demise.
Instead of using soap, Rabbi Yehuda HaNasi advises Rabbi Hiyya to slaughter a bird over the flax water, positing that the blood will attract the moths and cause them to drown. But he uses the verb “slaughter” which immediately creates a problem — because if the bird is slaughtered properly, its blood needs to be covered in earth, not deposited in the water.
From our study of the mishnah earlier on this daf, you can probably guess the solution: Do not actually slaughter the bird correctly. Instead, intentionally slaughter it incorrectly. Indeed, two options are presented along these lines.
When Rav Dimi came from the land of Israel, he said that Rabbi Yehuda HaNasi said to Rabbi Hiyya: Go out and render the bird a treifa.
When Ravin came from the land of Israel, he said that Rabbi Yehuda HaNasi said to Rabbi Hiyya: Go out and tear loose the bird’s windpipe and gullet.
By killing the bird through a method that is not kosher slaughter, one removes the obligation to cover its blood — freeing that blood up for use as a moth deterrent.Tomorrow, this sugya will conclude with the Gemara asking a different question about the moths in Rabbi Hiyya’s flax:
But doesn’t Ravin bar Abba say, and some say Rabbi Avin bar Sheva says: From when the people of the Exile ascended from Babylonia to the land of Israel there ceased to be meteors, earthquakes, storm winds, and thunder; and their wine did not sour, and their flax was not stricken with moths; and the sages placed their eyes (i.e., attributed these phenomena) to the merit of Rabbi Hiyya and his sons?
If all these damaging phenomena, including moth infestations, abated due to the merit of Rabbi Hiyya and his family, how could he himself have a moth infestation? The Gemara answers:
When their merit is effective, it is effective for the rest of the world but not for themselves.
Alas, everyone but Rabbi Hiyya was saved from the moths.
Read all of Chullin 85 on Sefaria.
This piece originally appeared in a My Jewish Learning Daf Yomi email newsletter sent on July 24, 2026. If you are interested in receiving the newsletter, sign up here.
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