Centipede

A Centipede is a type of bug found, like Pill Bugs, under rocks by striking it with a Shovel or an Axe. They can be found from 4 PM to 11 PM in all games. They are worth 300 Bells.

In
Upon donation to the museum, Blathers will say this about the Centipede:

The Centipede can be found on the second level, near the rafflesia, along with the Fly and Flea.

In
Upon being donated, the Centipede can be found in the upper left room of the bug exhibit, near the rafflesia. The exhibit has this to say about the Centipede:

In
When asked about the bug, Blathers will say the following:

The centipede can be found in the leftmost glass display with the Pill Bug and the Moth.

Real-world information
The centipede in this game appears to be the brown centipede, found in Europe. Unlike what most people think, centipedes are not insects. They actually belong to the class of animals known as Chilopoda, which are close relatives to millipedes and small myriapods known as symphylids.

Trivia

 * The Prima City Folk Guide incorrectly states in their bug guide that Centipedes are found on flowers instead of rocks. This may have caused confusion to some players looking for the Centipede.