Male Sheargrub

Male Sheargrubs can easily be distinguished from Female Sheargrubs by their dark purple color and large mandibles. Unlike the females, which are believed to scavenge dead Pikmin, Male Sheargrubs are predatory and extremely aggressive, and will attack leaders and Pikmin when the opportunity presents itself. Sheargrubs have lost both their legs and wings in an odd twist of evolution, and have adapted to a life spent mostly underground.

In Pikmin, these bugs are completely invulnerable while they're chomping down on a Pikmin except when a Pikmin is tossed directly on top of it. This was fixed in Pikmin 2, allowing players to kill them even if they have a Pikmin in their grasp. Sheargrubs, both male and female, will also deconstruct any nearby stick bridges, which makes defeating these pesky creatures soon after landing a top priority to avoid having to rebuild them.

These creatures are also related to the Shearwig, beyond sharing families. They are both male mandiblards that attack in the same fashion, and in some cases, specifically The Forest Navel, appear in large swarms together.

In Pikmin 3, they can regenerate health while buried, and are able to fully regenerate in 30 seconds, just like the Female Sheargrubs. If only 20% of their health remains, they return to their original spot to bury and heal, and when their health reaches 50%, they come out again, if there are any prey in range. While they're regenerating, their health wheel will be constantly visible above the ground.

Pikmin
The species is relatively weak compared to most other creatures, but if one happens to get a hold of a Pikmin, it is invincible to swarming until the Pikmin dies. If a single Pikmin is thrown onto the Sheargrub's back, it will die instantly, and the Pikmin will be saved. Attack with Olimar if possible, but be careful, as a bite deals massive damage. If there is water nearby, like in The Forest of Hope, lead them into it. Since they cannot fly, and will keep following their prey, they will eventually drown.

Pikmin 2
The male Sheargrub's mysterious invincibility is no longer present here, making them incredibly easy to kill. Simply swarm with a group of Pikmin and they'll have no chance. Same as in Pikmin, if there is a body of water nearby, lead them in and drown them.

Pikmin 3
Male Sheargrubs are much more rare in this installment, but can be a slight nuisance nonetheless. The invincibility is once again no longer present, so just use a good amount of Pikmin to take care of them. In this game, they are resistant to water. These enemies are also not known to be able to eat bridges like in previous installments.

Hey! Pikmin
Male Sheargrubs can appear from the ceilings or the floors. They are a big nuisance and will fall on your Pikmin, killing them. To kill it, throw a Pikmin at it once, but remember they come in groups.

Trivia

 * An alternative, fatter version of the Male Sheargrub exists unused inside Pikmin 3.
 * A singular Male Sheargrub appears on a stump near the paper bag in the Tropical Wilds Pikmin 3, but was removed in the Nintendo Switch rerelease, Pikmin 3 Deluxe, being replaced by a screw.