Giant mosquitoes often generate in large groups, and generally start appearing within the first few floors of the dungeon.
The giant mosquito is small and fast, and being surrounded by a large group of them can be a serious problem for a lower-level player without poison resistance.
Red Saunders said he could take anything. The men found a corner
of the island where thick clouds of mosquitos were hovering above
the still water. The workmen built a small, smoldering fire to
give off smoke that would give them some shelter. And Red stripped
off his shirt and lay face down in the mud, letting the mosquitoes
go to work on his back. And work they did. Red's back was soon
covered with the insects, digging in, drawing blood, and leaving
itchy welts behind. But Red didn't flinch. He just lay there,
letting the mosquitos feed on him, and only occasionally looking up
to say "I sure hope those mosquitos over there ain't getting to be
too much for y'all" to the men sheltering in the smoke. This went
on and on. But when about three-quarters of that hour had passed,
something happened. Red felt something bite into his back sharper
and more powerful than he had ever imagined. A searing, sharp pain,
bit into his flesh, and he heard one of the men by the fire yell out
[ The Legend of the Gallinipper,
Averasboro, North Carolina, circa. 1855 ]
There are in this country over thirty varieties of mosquitoes.
Some are small and others are quite large. Some live wholly on
vegetable juices, while others have a passion for animal fluids.
The largest, and perhaps the most ferocious kind, is one which the
steamboatmen of the Mississippi River call the galnipper. Of it
they tell strange stories. They describe it as being as large as a
goose; and they gravely declare that it flies about at night with a
brick-bat under its wings to sharpen its beak with.
[ Living Creatures of Water, Land and Air, by John Monteith ]