Flyspeck, also known as 1212 Muscae IV, is the fourth planet in the 1212 Mus star system. It is the homeworld of sentient Ornaet and Lahit races, and was watched over by the ;At.
Its nickname was coined by the sciences division of the Federation starship USS Enterprise, in recognition of the world being part a small system in the Musca constellation, which was Latin for fly.
Due to the presence of brightly-colored chlorophyll in the plant life, its surface appeared vibrantly green. Trees even had green-colored trunks. Flora ranked high as medicinal sources.
The Ornaet and Lahit races might have evolved from a common ancestor. (TOS novel: Doctor's Orders)
Starfleet conducted an initial survey in the 2270s which involved first contact with the three sentient species.
In 2275, a detailed follow-up survey was conducted by the crew of the USS Enterprise. (TOS novel: Doctor's Orders)
In the 2360s, the USS Enterprise-D orbited the planet. While surveying the surface, floral specialist Mark Stewart contracted a fungal infection. He also fell from a Lahit's tree-like body and broke his forearm. Both injuries were treated by Beverly Crusher. In 2367, she recalled those injuries while studying Stewart's counterpart from the mirror universe, who showed signs of having contracted the same fungal infection but had not broken his arm. (TNG novel: Dark Mirror)