Cancer

Cancer and crabs may be the names of medical conditions you don’t want to have, but in this context, it just refers to crabs, the awesome crustaceans that live in oceans, freshwater, and on land. They are characterized by their thick exoskeletons and pinchy claws. In Vergil’s Georgics, crabs are something you should NOT burn around bees.

Defining Cancer + Grammar
cancer, cancri, m - crab


 * cancer is also sometimes used to refer to the zodiac sign, or to summer heat

Appearances
4.47-48:  Neu propius tectis taxum sine, neve rubentes ure foco cancros

“Nor should you set a yew tree any nearer to the homes, or burn red crabs on the hearth”

From the commentary:

“The strong smell of roasted crabs (used as fertilizer) would scare the bees away; cf. Pliny NH 11.62; Colum. 9.5.6.”