Poisonous Beetle

The Poisonous Beetle is an enemy that was first introduced in the game Pikmin:The After Years. Unlike Anode Beetles, they have purple spots and emit poison when two of them meet. This attack will poison all but White Pikmin.

How to Kill
Throwing a White Pikmin on top if it will flip it over and because they are immune to poison, they won't get poisoned. A Purple Pikmin will also flip multiple of these beasts over due to the shock-waves they create.

-- Gamefreak75