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Mosquito Swarm

A high-pitched drone precedes the cloud of tiny insects that approaches like a malevolent thunderhead.

Mosquito Swarm CR 3

Source Rivers into Darkness pg. 29, Bestiary 2 pg. 193
N Fine vermin (swarm)
Init +4; Senses darkvision 60 ft.; Listen +4, Spot +8


AC 22, touch 22, flat-footed 18 (+4 Dex, +8 size)
hp 14 (4d8-4)
Fort +3, Ref +5, Will +1
Immune swarm traits, vermin traits, weapon damage


Speed 5 ft., fly 20 ft. (average)
Melee swarm (1d6)
Space 10 ft., Reach 5 ft.
Special Attacks attach, blood drain, distraction


Str 1, Dex 19, Con 8, Int —, Wis 10, Cha 2
Base Atk +3; Grapple
Skills Listen +4, Spot +8; Racial Modifiers +4 Listen, +8 Spot
SQ swarm traits, vermin traits


Environment any temperate or tropical
Organization solitary, cloud (2-7 swarms), or plague (11-20 swarms)
Treasure none
Advancement none

Special Abilities

Attach (Ex) If a living creature takes damage by being in a space occupied by the swarm at the end of the creature’s turn, hundreds of the mosquitoes from the swarm attach themselves and continue to deal blood drain damage. To remove the attached mosquitoes, the creature must deal at least 2 points of damage through an area effect (that affects the attacked creature normally as well) or submerge himself in water.

Damage dealt to mosquitoes attached to a creature does not count against the swarm’s hit points, unless the swarm is in the area of effect as well. Attached mosquitoes drain blood for 3 rounds before they become sated and fall off.

Blood Drain (Ex) A mosquito swarm deals 1 point of constitution damage per round from blood drain on any living creature that ends its turn in a space occupied by the swarm or any creature subjected to the swarm’s attach special attack, whether still within the swarm or not.

Distraction (Ex) Any living creature that begins its turn with a mosquito swarm in its space or while having mosquitoes from the swarm attached to it must succeed on a Dc 11 fortitude save or be nauseated for 1 round. The save Dc is constitution-based.


A mosquito swarm is a cloud of thousands of blood-sucking vermin that seek living prey to feast upon. A variant of the traditional mosquito, this particular species is significantly larger. Each specimen is roughly an inch long, which dramatically increases both the amount of blood each insect can drain from a potential victim, as well as the number of offspring each pair can produce. The males of this particular species die soon after mating, leaving the females to search for succulent blood to nourish the next generation. An attacking swarm is thus composed entirely of females. They prefer to feed on warm-blooded creatures.

Environment: Unlike traditional mosquitoes, this particular breed is extremely sensitive to cold temperatures and low humidity, meaning that they are largely confined to the jungles of the Mwangi Expanse. However, recently they have begun turning up in some of the more tropical ports along the Inner Sea, causing some to speculate that perhaps the increased trade to and from the Mwangi has lead to some unwelcome stowaways.

Typical physical Characteristics: Spindly insects with long proboscises for draining blood from their prey, perhaps the most terrifying thing about these swarms is that they rely on numbers rather than stealth to steal blood, and thus they are large enough that it’s easy to tell exactly what they are doing.