Water Beetle

The Water Beetle is an enemy that was first introduced in the game Pikmin:The After Years. Unlike Anode Beetles, they have blue spots and spray water when two of them meet. This attack will drown all but Blue Pikmin.

How to Kill
Throwing a Blue Pikmin on top if it will flip it over and because they are immune to water, they won't drown. A Purple Pikmin will also flip multiple of these beasts over due to the shockwaves they create.

-- Gamefreak75