Many organisms make a living from seratching each other's backs. and many survive at the expense of othcrs. Once a complex interaction has arisen between two organisms. what elfect can such a relationship have on their subsequcnt cvolution·! This pllpcr will consider thc evolutionary conscquences of ussocintions UIllOlIg Iycllcnid buttcrflics, their host plants, unts. purusitoids. lind prcdators. Thc Lycacllidac llfC cspecially intcrc.'1ting from an ccologicul and evolutionary pcrspcctivc because they exhibit dramatic variety in their life histories. The larvae of many species associate with ants, and these relationships can be parasitic. commensal, or mutualistic. larvae cun be carnivorous or hcrbivorous: and some species interact with many species of ants, whereas others are species-specific. It is partly because of this complexity and diversity that the lycaenidae have not been studied as intensively as other buUerny families, and I will discuss at least three problems that have hampered our understanding of their ecology and evolution. In particular. more must be learned about the nature of the exocrine secretions of lycaenid larvae, and whether they function to reward. appease, and/or deceive their associated ants. The association between lycaenids and ants has had several important evolutionary consequences, and I will show how these relate to the question of why there are so many species of Iycaenid buuernies. Finally. I will discuss an unresolved pattern in the biogeography oflycaenid buuernies: association with ants in general, and species-specific interactions in particular, are far more common among Iycaenids found in Ethiopian, Oriental. and Australasian regions than among those from the Holarctic.