Bed Bug

Bed Bugs are insects mentioned once in the How to Train Your Dragon Franchise.

Description
Bed Bugs (Family Cimicidae, Order Hemiptera) are a parasitic insect group known for its exclusive diet of blood. Different species specialize in specific host species. The "Common Bed Bug" (Cimex lectularius) primarily feeds on humans. Bed Bugs have a stylet fascicle - a "beak" or proboscis - that pierces and saws through the skin until a blood vessel is reached. Its saliva contains analgesics and anti-coagulants. Feeding is complete in about 5-10 minutes. Bed Bugs are nocturnal and will return to their hiding place during the day whether they have gotten a blood meal or not.

Function
Bed Bugs have no usage in the Franchise or in real life. They are, however, a major pest of humans. Presently, they are not known to be vectors of any diseases.

Dragons: Race to the Edge, Season 2
In the episode "A Time to Skrill", Ruffnut and Tuffnut guess what could have driven the Outcasts off their island. Ruffnut guesses it were bed bugs.

"Bed bugs? Once those things show up, you can never get rid of 'em."

- Ruffnut guessing