Since we've run out of unconverted "real world" spiders, here are a couple of giant flies.
Insect #AP AC MV HD THAC0 # of Att Dmg/Att Morale XP Value
Fly, Bluebottle 1-10 6 9, Fl 30 (D) 3 19 1 1-8 Unsteady (5-7) 65
Fly, Horsefly 1-4 5 6, Fl 27 (D) 6 17 1 2-16 Unsteady (5-7) 270
Fly, Giant Bluebottle
This breed of giant fly prefers carrion, offal, and the like. They are, however, attracted to sweet odors, and creatures covered with blood or open wounds.
Fly, Giant Horsefly
The largest of all giant flies, the giant horsefly alights on any creature to attack for blood with its tuberous mouth. After biting, the giant horsefly causes an equal amount of damage the next round by drawing blood, unless driven off.
Originally appeared in Monster Manual II (1983). These are the Monstrous Manual versions.
Blue bottle fly - Wikipedia, the free encyclopedia
Horse-fly - Wikipedia, the free encyclopedia
WotC's 3e giant fly:
Dead Life