Sexual communication in day - flying Lepidoptera with 3 special reference to castniids or ‘ butterfly - moths ’ 4 5 Víctor Sarto

28 Butterflies and moths are subject to different evolutionary pressures that affect several aspects 29 of their behaviour and physiology, particularly sexual communication. Butterflies are day30 flying insects (excluding hedylids) whose partner-finding strategy is mainly based on visual 31 cues and female butterflies having apparently lost the typical sex pheromone glands. Moths, 32 in contrast, are mostly night-flyers and use female-released long-range pheromones for 33 partner-finding. However, some moth families are exclusively day-flyers, and therefore 34 subject to evolutionary pressures similar to those endured by butterflies. Among them, the 35 Castniidae, also called ‘butterfly-moths’ or ‘sun-moths’, behave like butterflies and, thus, 36 castniid females appear to have also lost their pheromone glands, an unparallel attribute in the 37 world of moths. In this paper, we review the sexual communication strategy in day-flying 38 Lepidoptera, mainly butterflies (superfamily Papilionoidea), Zygaenidae and Castniidae 39 moths, and compare their mating behaviour with that of moth families of nocturnal habits, 40 paying particular attention to the recently discovered butterfly-like partner-finding strategy of 41 castniids and the fascinating facts and debates that led to its discovery. 42 43