Red Midges/Gnats (Yavchushin Adumin)

Red midges/gnats are a type of sheretz (creeping thing) that develops in water or wine that has been stored in a wooden barrel for a long time.

In Laws of Immersion and Hand Washing

In the Talmud, it states that red midges are sheratzim created from water, as Chazal phrase it "their initial creation is from water," and therefore they are defined in certain halachic definitions as water for almost all matters. In Masechet Zevachim, it mentions that it's even possible to create an entire mikvah composed solely of the bodies of these midges.

Some commentators explain this refers to a case where they were crushed until they became water-like. Others permit immersion in such a mikvah even without crushing them. In Shulchan Aruch HaRav, the Alter Rebbe rules that in pressing circumstances, one may rely on the first opinion to be lenient, in cases where the obligation to immerse is d'rabbanan (rabbinical).

However, regarding washing hands, there is consensus that only if the midges are crushed until they become a liquid substance like water, can one fulfill the mitzvah of hand washing with them.

Permissibility for Consumption

Regarding issues of prohibition and permissibility, the Gemara determines that if the midges are mixed with the water in which they were created and have not yet separated from the water, they are permitted for drinking since they are defined as water. These midges are not called "red midges" in the language of the Gemara, and it's not clear if these are the same midges.

In Our Times

One of the sheratzim that fits Rashi's identifying features is the non-biting midge (scientific name: Chironomus) or sometimes called "tufted mosquito," which is a genus in the family Chironomidae. The larva develops in various aquatic environments such as puddles and lakes, and it is very common in Eretz Yisrael. The wingless larvae have a reddish-brown body color due to the hemoglobin dissolved in their blood, hence their name "red midges."