Locust Swarm, Bloodfiend (CR 8)

Medium Vermin (Extraplanar and Swarm-Fine)
Alignment: Always chaotic evil
Initiative: +4 (Dex)

AC: 19 (+4 Dex, +5 natural), touch 14, flat-footed 15
Hit Dice: 14d8+28 (91 hp)
Fort +11, Ref +8, Will +5
Speed: 20 ft., fly 20 ft. (perfect)
Space: 10 ft./0 ft.
Base Attack +10; Grapple -
Attack: Swarm
Full Attack: Swarm
Damage: Swarm 3d6 plus energy drain
Special Attacks/Actions: Distraction (DC 19), energy drain
Abilities: Str 1, Dex 18, Con 14, Int -, Wis 13, Cha 11
Special Qualities: Reanimate, swarm traits, vermin traits
Feats: -
Skills: -
Advancement: -
Climate/Terrain: Any land and underground (Abyss)
Organization: Solitary or plague (10-40 swarms)
Treasure: -

Source: Fiend Folio

Whereas the common locust poses a menace only to plants and crops, deadlier strains, influenced by magic or fiendish will, attempt to tear the flesh from any creature they encounter. These creatures, although too small individually to pose a threat to most creatures, can quickly engulf and devour unprepared victims.

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.