Shimmerwing Butterflies

Shimmerwing butterflies are only found on the island of Ascalon, in the Sea of Monsters. Their symbiotic partnership with the wingless manticores of the island is particularly unique.
Ascalon is a long, narrow island with many active volcanoes dotting its length, and covered in a tropical rainforest. Molten fragments of rock hurled from the constant eruptions frequently start spot fires which are equally swiftly put out by the damp conditions and regular rainfall. Life in this environment is both hardy and accelerated, with organisms on the island developing a variety of mechanisms to hunt and feed.
Giants of the butterfly species, each wing is the size of a large man's spread hand, and covered with shimmering iridescent patterns like oil on water or highly polished metal. The wings of the butterflies reflect light in shifting and hypnotically brilliant patterns. These patterns will commonly entrance an animal watching as the butterfly seemingly aimlessly adjusts and fans its wings. The butterfly will continue this performance until one of the many manticores roaming the island happens upon the scene, and attacks the butterfly's prey.
The wingless manticores more closely resemble great apes with enormous lion-like ruffs, and their tails do not hurl spines as their cousins' do. Instead, they are equipped with a scorpion like stinger with a massively potent poison. When the manticore discovers fascinated prey, it will instantly stab the creature with its stinger, the poison swiftly stopping its heart. As the manticore starts to dismember the prey, the butterfly descends to drink the blood of its victim. The butterflies have evolved an immunity to the manticores' venom, and the manticores never attack the butterflies. The two co-exist ruthlessly.
Clouds of shimmering iridescent colour quickly swirl out of the trees as nearby butterflies respond and join the feeding frenzy, until the entire area seems coated in flashing sparkles of light. As the butterflies gorge themselves the veins in their wings flush red, and the reflections shift to match. The scene appears to be suffused in bloody light with a moving, rustling carpet of glinting blood across the ground.