Derpling

Derpling spawns in the Jungle when Hardmode is activated. This buglike monster jumps high and attempts to land on you. It can strafe to the sides in midair, making it a pain to deal with. One is advised to deal with them quickly, as they spawn fast and can easily overwhelm you. They are immune to the Confused debuff.

Trivia
There is also crimson counterpart, the Herpling. The Derpling and the Herpling are probably references to the meme "Herp Derp"