Tiddly-Nip Tick-Botherers are nanodragons, meaning they are very small, possibly as small as an insect. In The Incomplete Book of Dragons, these dragons appear to have yellow skin and a short tail. Also in that reference book, there is another individual with remarkably bigger eyes than the one pictured below.
It might be inferred from their name that Tiddly-Nip Tick Botherer's prefer eating ticks. If so, this certainly would be very useful to Vikings and livestock. These particular species of nanodragon can speak Dragonese.
The Tiddly-Nip Tick-Botherer is first seen and described in this reference book for the How to Train Your Dragon Book Series.
The Tiddly-Nip Tick-Botherer appears in the final Book of the series when Ziggerastica, king of the Nanodragons, brings his retinue to help Hiccup secure his claim to the throne of the Wilderwest. Countless nearly invisible nanodragons lift Hiccup into the air, giving him the appearance of levitating.