Stirge

This horrid flying creature looks like a cross between a large bat and an over-sized mosquito. Its legs end in sharp pincers, and its long, needle-like proboscis slashes the air as it seeks its next meal.
Stirges feed on the blood of living creatures, attaching and draining them slowly. Although they pose little danger in small numbers, packs of stirges can be a formidable threat, reattaching as quickly as their weakening prey can pluck them off.

Blood Drain

A stirge attacks by landing on a victim, finding a vulnerable spot, and plunging its proboscis into the flesh while using its pincer legs to latch on to the victim. Once the stirge has sated itself, it detaches and flies off to digest its meal.