There are a handful of monsters that can trace their roots back to the beginning of Dungeons and Dragons. There are even fewer that players dread to face. The Stirge is one such creature. Throughout the editions the Stirge is one of the iconic monsters that has managed to stay intact.
Most players willingly wade into battle to face off against fearsome monsters like dragons and Minotaur. But the lowly Stirge is a beast that many players simply fear. Maybe it is because so often they are encountered at lower levels. Facing them is never a pleasant business. Likely it is simply fact that there is no glory falling prey to these foul creatures. After all what is not to fear from a flying cat sized mosquito!
The Stirge has had many incarnations over the years. Some far more scary than others. In 1st ED D&D it was not so much that the Stirge itself was so scary. It was that you never encountered a lone Stirge. In the first incarnation of D&D they appeared in groups of 3-30! Added to this they attacked as 4th level fighters! A decent number of Stirge could easily lay an unsuspecting party low without much difficulty and fly off to feast another day with bellies bloated from the blood their victims.
In 3rd ED The Stirge became a terrifying creature. As now its blood drain ability now drained Attribute points. Players of any level could quickly find themselves drained husks. Defeated to the likes of a giant bat like insect. In their 4th Edition the Stirge was toned down from the 3 E version returning back to HP drain over Attribute drain. But they now also could be found two new flavors of DIRE and Swarms! In the latest edition the Stirge has returned to its roots looking very much like its 1E cousin only that it hits twice as hard.
In the end the Stirge is just good fun monster lovers monster.