Swarm vs. Swarm

[Scharlata]

From here:

Types, Subtypes, and Special Abilities Swarm Subtype: ...

A swarm’s attacks are nonmagical, unless the swarm’s description states otherwise. Damage reduction sufficient to reduce a swarm attack’s damage to 0, being incorporeal, and other special abilities usually give a creature immunity (or at least resistance) to damage from a swarm. Some swarms also have acid, poison, blood drain, or other special attacks in addition to normal damage.

What kind of DR? DR/--, or does it have to be a specific kind of damage, like B, S, or P? If yes, which of the three kinds is relevant?

 

[Patryn of Elvenshae]

What kind of DR?

Pretty much any, for most swarms. Swarm attacks, unlike, say, claws, aren't given a damage type. So, you'll likely need to type it ad hoc, but it's probably like a bite: slashing, piercing, and bludgeoning.

As for other DR types ...

A hellwasp swarm’s attack is treated as an evil-aligned weapon and a magic weapon for the purpose of overcoming damage reduction.