Damselfly

The Damselfly is a bug introduced in. It is similar to a dragonfly, but unlike the Darner Dragonfly, Red Dragonfly, and Banded Dragonfly, it only appears in winter.

In
Blathers has this to say about the Damselfly:

Once donated, the Damselfly is found in the main room of the bug exhibit, flying around near the waterfall at the northern end of the room. It shares this area with the Red Dragonfly, Darner Dragonfly, and Banded Dragonfly.

Real-world information
Damselflies are insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller, have slimmer bodies, and most species fold the wings along the body when at rest, unlike dragonflies which hold the wings flat and away from the body. An ancient group, damselflies have existed since at least the Lower Permian, and are found on every continent except Antarctica.