Giant fly

The giant fly was the metamorphosed form of one of the giant maggots. Despite its great size, it could fly. It attacked the UNIT soldiers, squirting poisonous slime at them. The Third Doctor swatted it with his cape. The Doctor bemoaned the fly's death, saying that it was "beautiful in its own way". The rest of the giant maggots had been poisoned by Professor Clifford Jones' fungus before they had a chance to metamorphose also. (TV: The Green Death)