Common bluebottle

The Common Bluebottle is a bug that was added in. As its name suggests, it is a common bug. It can be seen flying around during the day from April to August. Unlike other butterflies, it can sometimes be seen resting on the ground, though it will resume flying after a short time or if the player is nearby. It sells for 300 Bells.

In
"The common bluebottle is a type of swallowtail butterfly with a bright blue line running down its wings. They fly quite nimbly, it seems, and are thus quite difficult to catch. But seeing how they've been known to slurp nutrients from MUD puddles... I simply CAN'T imagine wanting to catch one myself. What awful breath! "

Once donated, the Common Bluebottle can be found flying in the butterfly room in the Bug Wing at the Museum.

Real-world information
Graphium sarpedon, also known as the "common bluebottle" or "blue triangle", is a butterfly native to southeast Asia and eastern Australia.

Trivia

 * "Bluebottles" are also a type of blowfly, but the Common Bluebottle is a butterfly.