A carrion diver is a flying insect that is known to feed on plants (including Rhododendrons). Probably native to The City, this creature is largely unknown. Although the Insect Swarms seen around corpses and the like are often said to be carrion divers, there is no real evidence to support this assumption. Only the name "carrion" suggests such a relationship.
The spider Longdaddy was able to capture the Carrion Diver in a web.