From Nookipedia, the Animal Crossing wiki
The Longhorn Beetle (カミキリムシ, Kamikirimushi) is a bug that can be found in all versions of Animal Crossing. It is quite common - it appears on trees in early Animal Crossing games, but on tree stumps in Animal Crossing: City Folk and Animal Crossing: New Leaf.
Donating to the Museum
In Animal Crossing
"Hoo my! Those sharpish mandibles... truly frightening. Honestly, what could be more off-putting than these? And the antennae! Why on earth are they so very thick? Blech! Most objectionable! In a word: bad!"
In Wild World
"Hoo, I say! Be sure to keep your fingers away from that savage maw! And what ostentatious antennae! I mean, really! Blech! Such foulness... Hoo... But I digress..."
After Blathers reluctantly accepts the Longhorn Beetle, it can be found on the third tree from the right in the second room of the bug exhibit. It sits placidly on its tree, but does shuffle about on the spot quite a bit.
In City Folk
"The multiple varieties and colorful body types of the longhorn beetle make it popular with collectors. It stands toe-to-toe with the dynastid and stag beetles in its popularity with children, eh wot? But those long, skinny legs and long antennae drop it right off this owl's list! How utterly revolting..."
After donation, it can be found on the second tier of the insect section of the museum, in the middle enclosure containing two trees and a tree stump, on the tree stump with the Violin Beetle. This enclosure also contains the Walking Leaf and Oak Silk Moth, to name a few others.
Bug Encyclopedia information
The genus is the Anoplophora of the longhorn, the Cerambycidae is the family. Native to China, the Asian long-horned beetle causes severe damage to America's trees. The beetle can launch itself as far as 400 meters, in search for a tree to lay eggs in. As they grow up, they wiggle out of trees, eating sap, laying waste, and making deep, wide holes.
Names in other languages