Boa, Rochester Bestiary, c.1230

As other medieval bestiaries, the Rochester Bestiary records that the boas is a large snake that follows sheep and cattle. They kill them by hanging from their udders and sucking them dry.

Transcription

Translation

Boas anguis italie inmensa mole; greges
armentorum. et bubalos. et plurimo lac-
te uberibus innectit. et suggens inte-
rimit. Atque inde a boum depopulatione; boas dcitur;

Boas are snakes in Italy that grow to enormous size. They fill themselves with a great deal of milk from the herds of cattle and buffaloes, killing them. And hence from the depopulation of cattle, it is called boas.