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Giant Fly, Horsefly

insect, living nature, animals, Giant Fly, Horsefly

This massive fly approaches with a thunderous din from its rapidly beating wings.

Originally Posted by Shade of the En World forums.

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Giant horseflies are among the largest of their kind. They feed upon nectar and pollen of giant plants, and the blood and flesh of large mammals, birds, and other animals.

Giant horseflies lay their eggs on leaves, stems, or stones near water. On hatching, the larvae fall into water or moist earth, feeding voraciously on anything smaller than themselves.

A giant horsefly is 4 to 6 feet long with a 10-foot wingspan and weighs around 500 pounds.

Fly, Giant, Horsefly
Large vermin
Hit Dice6d8+18 (45 hp)
Speed20 ft. (4 squares), Climb 20 ft., Fly 60 ft. (good)
Armor Class15 (-1 size, +2 Dexterity, +4 natural), touch 11, flat-footed 13
Base Attack/Grapple+4/+11
AttackBite +6 melee (2d8+4 plus wounding)
Full AttackBite +6 melee (2d8+4 plus wounding)
Space/Reach10 ft./5 ft.
Special AttacksDisease, wounding
Special QualitiesDarkvision 60 ft., evasion, resistant to disease, Scent, vermin traits, wallcrawling
SavesFort +8 (+12 vs. disease), Ref +7, Will +2
AbilitiesStrength 17, Dexterity 15, Constitution 16, Intelligence -, Wisdom 10, Charisma 2
SkillsClimb +11, Listen +2, Spot +2
FeatsDodge (B)
EnvironmentAny land and underground
OrganizationSolitary or swarm (2-4)
Challenge Rating3
AlignmentAlways neutral
Advancement7-9 HD (Large); 10-18 HD (Huge)
Level Adjustment


The giant horsefly’s mandibles resemble serrated scimitars, which they use to rip and slice flesh, leaving vicious wounds. The horsefly laps up the flowing blood, or carve off a chunk of meat to digest at its leisure. Giant horseflies often spread a variety of blood-borne diseases (this one carries Red Ache).

Disease (Ex): Red Ache – bite, Fortitude DC 16, incubation period 1d3 days, damage 1d6 Strength. The save DC is Constitution-based.

Resistant to Disease (Ex): A giant horsefly has a +4 racial bonus on Fortitude saves vs. disease.

Wallcrawling (Ex): A giant horsefly need not make Climb checks to traverse a vertical or horizontal surface (even upside down). It retains its Dexterity bonus to Armor Class while Climbing and opponents get no special bonus to their attacks against it.

Wounding (Ex): On a successful hit, a giant horsefly’s bite attack deals 1 point of Constitution damage from blood loss in addition to normal damage. A critical hit does not multiply the Constitution damage. Creatures immune to critical hits (such as plants and constructs) are immune to the Constitution damage caused by wounding.

Skills: Giant horseflies have a +2 racial bonus on Listen and Spot checks and a +8 racial bonus on Climb checks. A giant horsefly can always choose to take 10 on Climb checks, even if rushed or threatened.

Originally appeared in Monster Manual II (1983).

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