From the Super Mario Wiki, the Mario encyclopedia
The Beetle is a large, green beetle in purple racing gear that appears in Donkey Kong 64. She is raced twice, first by Tiny Kong in Angry Aztec and later by Lanky Kong in Crystal Caves. In each race, when either Kong wins, they are rewarded a Golden Banana.
In Angry Aztec, Tiny can challenge the Beetle by using Mini Monkey and playing Saxophone Slam from a nearby Music Pad. This causes Squawks to appear, and he picks up Tiny and throws her into a tower with the Racing Beetle. The race involves Tiny and the Beetle racing down a large slide. When the race Starts, Tiny can kick the Beetle to slow her down, allowing Tiny to get a headstart. The Beetle is almost the width of the slide, making her hard to avoid. Tiny's objective is to first collect at least 50 DK Coins before finishing the race. If the Beetle knocks into Tiny, she loses three DK Coins.
In Crystal Caves, Lanky has to race the Beetle, this time by using his OrangStand Sprint.