What damage type do swarms do?

[Voadam]

Here is the text on swarm attacks:

Quote:

Swarm Attack: Creatures with the swarm subtype don't make standard melee attacks. Instead, they deal automatic damage to any creature whose space they occupy at the end of their move, with no attack roll needed. Swarm attacks are not subject to a miss chance for concealment or cover. A swarm's statistics block has “swarm” in the Melee entry, with no attack bonus given. The amount of damage a swarm deals is based on its Hit Dice, as shown below.

Swarm HD

Swarm Base Damage

1–5
1d6

6–10
2d6

11–15
3d6

16–20
4d6

21 or more
5d6

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, or other special abilities usually give a creature immunity (or at least resistance) to damage from a swarm. Some swarms also have acid, blood drain, poison, or other special attacks in addition to normal damage.

Swarms do not threaten creatures, and do not make attacks of opportunity with their swarm attack. However, they distract foes whose squares they occupy, as described below.

Swarms possess the distraction universal monster rule. Spellcasting or concentrating on spells within the area of a swarm requires a caster level check (DC 20 + spell level). Using skills that involve patience and concentration requires a DC 20 Will save.

In our group we know that we are going against vescavor swarms (biting demon vermin swarms). I have the spell resinous skin which gives DR 5/piercing but I'm not sure if I should expect them to do piercing damage.

I can't find a general bestiary statement on what type of damage swarms do. Is it dependent on GM interpretation and so generally be bite which is b/s/p? Is it untyped and subject to the resinous skin DR?

[Drone]

Page 302 of the Bestiary lists the different attack types and what type of damage is dealt. Bites are listed as Bludgeoning/Slashing/Piercing. Most swarms deal bite type swarm damage so the damage shoudl be considered ALL of those types. In your case, their damage would bypass your DR.
Wasp or bee swarms would do only piercing damage due to their stings are their primary form of attack. They would still bypass your DR/piercing but not someone with DR/slashing or DR/bludgeoning.

[thorin001]

Look at the base creature. The type of attack that the base creature makes will be the type of attack that the swarm makes.

As mentioned above, the Bestiary will tell you what type of damage each attack type does.