The Orion wing-slug was a type of animal lifeform native to the Rigel star system. Though known as one of the most unpleasant and less appealing creatures in the galaxy, they were however considered a delicacy by the Orions (presumably when properly prepared and cooked).
A full-grown Orion wing-slug was 5-10 centimeters long and weighed 10-20 grams, and had four membranous wings and an oozing slug- or snail-like body. They were usually a brownish-green, but different varieties had different revolting color schemes, ranging from a purplish taupe to a bruise black. They were scavengers that fed on carrion.
They mainly deterred predators by their awful smell and revolting taste. A secondary defense was their mildly caustic mucus, which caused a lingering burning sensation on soft tissues (such as the mouth, eyes and so on). On normal exposed skin, it would take a number of wing-slug impacts to raise a rash, but this would last for days of subtle, burning irritation.
During mating years, they gathered in vast swarms, numbering in the millions, and traveled across the habitable surfaces of the planets of the Rigel system. In the heat of the Rigel sun, they reeked from their slime, which they left on everything they touched or passed during their migration. They preferred wetter areas, such as canals, marshes and lakes, and the oases of Rigel VII.
Rigel II, Rigel III, Rigel V, and Rigel VII were all afflicted by wing-slug swarms, but all claimed that it was native to a different planet. When conditions allowed, they launched massive eradication campaigns against them. A swarm was a hazard to atmospheric craft, capable of jamming sensors, choking gas intakes, and splattering on view ports. (Decipher RPG module: Creatures)
When Gary Mitchell heard that James T. Kirk was being reassigned to the USS Constitution to serve alongside him, Mitchell considered himself to be as happy as "a sloppy, fat Orion with a belly full of warm, juicy wing-slugs". (TOS - My Brother's Keeper novel: Constitution)
Several live wing slugs were kept in bowls in a dining hall on the Orion station Mephil Trantos, where Kestralnamen enjoyed eating them. They were boiled on an Orion firepot nearly to the point of death, where they let out faint, high-pitched screams, then drank. (DS9 novel: Wrath of the Prophets)