You see a butterfly
Notes
The blue butterfly is semi-rare and moves faster than the Purple Butterfly.
Their dead bodies can be put in a Butterfly Conservation Kit to be used in The Explorer Society Quest.
Abilities
None.
Damage Taken From Elements
Physical 
Death 
Holy 
Ice 
Fire
Energy
Earth
Location
Yalahar, Tiquanda, the Shattered Isles, Cormaya Garden, Carlin Surroundings (near the Tired Tree), Kazordoon Surroundings (near the Grumpy Stone) and some other places.
Behaviour
A butterfly does not attack. A butterfly will retreat at 2 (100%, full) health.
Strategy
Just attack. Since it doesn't drop any loot, you should just leave it alone unless it gets in your way.