
Wizjolnir |

The rules about CMD say that a creature get +2 bonus on CMD per leg over his two first legs.
But the giant fly has :
Str 12, Dex 17, Base Atk +1; CMB +2; CMD 15 (21 vs. trip)
15 + (3 x 2) = 21 for 3 more legs over the two first legs which gives a giant fly with 5 legs
no ?
Or maybe CMD is 15 (23 vs. trip) with 6 legs instead ?

Wonderstell |

Oh. But there is a perfectly logical explanation.
You know how flies always make a perfect imitation of an evil mastermind rubbing their hands together? Yeah that's two legs out of the equation. And since a fly's proboscis is essentially always touching the ground, one would assume it grants the stability of an extra leg; granting the fly 5 legs, mechanically speaking.
...And who would ever think about tripping a fly? They can fly, after all.
Jokes aside, it is very probably just an error.

Ziere Tole |

They got the Fly skill wrong as well. They forgot Racial +8 for having a fly speed. They remembered it for the Climb skill.
/cevah
Racial bonuses to the Fly skill are based on maneuverability, they aren't a flat +8 like climb and swim. Giant Flies have Good maneuverability for Fly, so they just get a +4 on Fly, which adds up correctly.