Mothman (Impediment)

"Mothmen" (as they've been nicknamed by Allen Kirk) are a sapient spacefaring insectoid species hailing from a light-gravity world, which communicate by telepathy among themselves.

Biology
Like their name indicates, Mothmen are insectoids which closely resemble Earth's lepidopterans, only several times bigger. Their bodies are silver-colored and measure about 5 ft (~1.52 m), with a wingspan of less than 8 ft (~2.43 m), which allows them to fly under their homeworld's gravity. They can breathe Earth's atmosphere and survive on Earth food, but their exoskeletal system is not suitable for Earth's gravity.

Mothmen have three pairs of thin spidery limbs, consisting of two pairs of legs and one pair of arms. In addition to these, they also have two pairs of membranous wings, a pair of lidless yellow eyes more than 3 inches in diameter, and a pair of feathery antennae which can receive and broadcast thoughts. The antennae measure about 8 inches in length (20.32 cm) in most individuals, but can grow up to 18 inches (45.72 cm) in those who specialize themselves as "heralds".

Although they are capable of hearing, Mothmen have no spoken language and communicate solely by telepathy, which works by sensing the electrical activity of their nervous systems. While this allows them to communicate effortlessly with any other member of their species, it cannot be used to communicate with other species, since the Mothmen have no means to naturally discern the meaning of alien thought patterns. To communicate with other species requires a long period of learning, not dissimilar to how beings who talk verbally would need to learn a new language.

Mothmen don't have hearts. Instead, they have a system of valves and muscular rings along the full length of their blood vessels. Their respiratory system includes breathing vents and lungs. Like Humans, they typically sleep at night.

Culture and society
Mothman society operates under a feudal structure similar to Medieval Europe, with a hierarchy of ranks analogous to kings, lords and dukes, which are continuously at war with each other.

Their technology includes spaceships, but not spacesuits, since their anatomy makes it impossible to design a functional spacesuit that would allow movement of all their limbs and wings and supply oxygen to their breathing vents. Rivaling nations operate in space as pirates, and must disable their enemies' ships and tow them to a habitable world to be looted.

Appearances

 * "Impediment", by Hal Clement (1942)