Giant Firefly (CR 1/2)

Large Vermin
Alignment: Always neutral
Initiative: +2 (Dex); Senses: darkvision 60 ft. and Spot +7

AC: 13 (-1 size, +2 Dex, +2 natural), touch 11, flat-footed 11
Hit Dice: 3d8+6 (19 hp)
Fort +5, Ref +3, Will +2
Speed: 20 ft., fly 50 ft. (good)
Space: 10 ft./5 ft.
Base Attack +2; Grapple +1
Attack: Bite +4 melee
Full Attack: Bite +4 melee
Damage: Bite 1d3+4
Special Attacks/Actions: -
Abilities: Str 16, Dex 15, Con 14, Int -, Wis 12, Cha 13
Special Qualities: Vermin
Feats: -
Skills: Hide -2, Spot +7, and Survival +7
Advancement: 4-6 HD (large); 5-9 HD (Huge)
Climate/Terrain: Temperate hill and forest
Organization: Solitary or swarm (5-20)
Treasure/Possessions: None

Source: Arms and Equipment Guide

These vermin make excellent search and rescue creatures. Their abdomens glow a soft yellow or green and shed light in a 10-foot radius.

A common trick that riders direct giant fireflies to perform is "light." This keeps a firefly's phosphorescent abdomen lit indefinitely while the riders search for ground targets. Giant fireflies make poor combatants, so their riders flee battle as soon as possible. A giant firefly is 9 feet long.