• Pouring beer through wood chips prohibits the worms which separate onto the chips

Rav Huna said: לא לשפי אינש שיכרא בצבייתא באורתא – one should not pour beer through wood chips at night to filter it, because perhaps a worm will separate from the beer onto the chips and fall back into the cup. Although it developed in the beer and was initially permitted, once it crawled onto the wood chips, it becomes forbidden as שרץ השורץ על הארץ – a sheretz which creeps on the ground. The Gemara asks that if so, it should be forbidden to drink from the כלי, because perhaps the worm crawled onto the wall of the כלי and fell back into the beer!? It answers: התם היינו רביתיה – there, [the inner wall of the כלי] is its natural habitat, and is not considered creeping on the “ground.” This distinction can be proven from the Baraisa on the previous Daf, which permitted drinking out of בורות, without concern of worms inside. There, too, we are not concerned that a worm crawled onto the wall of the pit and fell back in, because it is its natural habitat. Rav Chisda supported this further from a Baraisa which prohibits gnats which were filtered out of wine, implying that before they were filtered out, they are permitted.

• Attached fruit which became wormy

Shmuel said: קישות שהתליעה באביה – a cucumber which became wormy while attached to the ground is forbidden under the prohibition of השרץ השורץ על הארץ – a sheretz which creeps on the ground; since the attached cucumber is considered the ground itself, the worm’s movement inside the cucumber is tantamount to having crept on the ground. The Gemara attempts to support this distinction, but the proof is deflected. Several questions are asked: פרשה ומתה – if [a worm] left the fruit and died when it reached the ground before walking, is it prohibited? What if only מקצתה – part of it left the fruit? What if it only reached לאויר העולם – to the open air but not the ground? What if the worm only reached the outside surface of the date, or the roof of the pit, or it crawled from one date to another? These questions are all left unresolved.

• "קוקיאני" – worms in fish prohibited, larvae found in meat are prohibited, in fish are permitted

Rav Sheishess brei d’Rav Idi said: "קוקיאני", worms which infest the livers and lungs of animals (Tosafos says that they infest fish), are forbidden, because מעלמא אתו – they come from elsewhere, and do not germinate inside the animals themselves. Rav Ashi objected that if they come from elsewhere, they should be found in the animal’s digestive tract!? Apparently they do germinate inside the animal, and should be permitted. In another version, Rav Shisha brei d’Rav Idi permitted קוקיאני, because מיניה גבלי – they are formed from [the animal] itself (i.e., germinate inside it). However, the halachah is that they are prohibited, because מינם ניים ועיילי ליה באוסייה – while [the animal] sleeps they enter through its nostril, which is why they are not found in the digestive system. The Gemara says that דרני דבשרא – larvae found in meat are forbidden, but דכוורי – larvae found in fish are permitted. Ravina explains: animals’ meat becomes permitted through shechitah, and since the shechitah is ineffective for larvae, they remain forbidden (as אבר מן החי). In contrast, fish become permitted through אסיפה – gathering from the water, so the larvae which develops in them are formed in a permitted state.