Male butterfly

The male butterfly is a giant butterfly that currently resides in The Butterfly Preserve. The Male Butterfly can be identified by his orange, yellow & black colouration, and enormous butterjunk. The male can also be identified by his large size and aggressive behaviour toward other mammals (This line however is not stated in the episode this is based on actual appearance). The male butterfly also produces a foul smelling liquid from its butterjunk that is foul to many people except butterflies and people who are afflicted to Nectar. This is what caused Amy & Leela to be attracted to Fry after he was sprayed because of angering the male butterfly.

Additional Info
Anyone who is sprayed by the liquid form the butterfly, turns into a butterfly (Fry). However, the effects ware off in time.