Source: Monster Manual (2024) p. 299. Available in the SRD and the Free Rules (2024)
A single stirge is usually little more than an annoyance, but several can be deadly if they attach faster than a victim can remove them.
Stirges
Notorious, Clinging Bloodsuckers
Habitat. Desert, Forest, Grassland, Hill, Mountain, Swamp, Underdark, Urban
Treasure. None
Stirges are bat-size vermin with dagger-length proboscises that attach to other creatures and drain life from them. Stirges are most active at night and hide in shadowy places during the day. If disturbed, they take flight and defend themselves. Roll on or choose a result from the Stirge Roosts table to inspire where stirges might lurk.