Emperor butterfly

The Emperor Butterfly (known as the Emperor prior to ) is an uncommon butterfly that is found around flowers in the summer months, late in the day. It is the only butterfly that can be found in the night. It is sold for 4,000 Bells in New Horizons, and 2,500 Bells in prior games.

Donating to the museum
As with all fish and bugs in the, the Emperor Butterfly can be donated to the museum by talking to Blathers, the curator. When donating, Blathers will say the following upon receiving the Emperor Butterfly:

In
After donation, the Emperor can be found fluttering around the flowers in the first room of the insect exhibit.

In
It can be found in the bottom terrace, flying near or resting on the flowers with any other butterflies.

In
Upon being donated, the butterfly can be found in the first room of the bug exhibit resting on flowers with the other butterflies. The exhibit has this to say about the Emperor Butterfly:

In
When the player donates an emperor butterfly, Blathers will say this about it before thanking the player for the donation:

Real-world information
Morpho menelaus, more commonly known as the Blue Morpho, is an exotic butterfly that can be found in Central and South America. It feeds primarily on rotten fruit, but in the larval stage, frequently eats other larvae of the same species. The in-game name Emperor Butterfly, while not used to refer to its species, may originate from the species' family, "Nymphalidae'', which is sometimes known as the Emperors.

Etymology
Morpho stems from the Greek word for form, and therefore means 'changed'. This may be a reflection of the species' iridescence, which has the quality of changing colors in the light. Menelaus was a legendary king of Sparta who married Helen of Troy.