Lepidoptera

There are a number of butterflies that live at least part of their life in close association with ant species.

Introduction
Obregon et al. (2015) provide an overview and introduction to this topic. Caterpillars of butterflies have evolved defensive adaptations to limit attack from natural enemies, including parasitoids. The most striking mechanism of this kind is probably the mutualistic relationship that lycaenid larvae have developed with ants (Pierce et al., 2002; Seymour et al., 2003). Various scenarios have been proposed to explain this complex behavior. Thomann (1901) first suggested that the ants keep parasitoids away, thereby benefiting the larval instars (see also Pierce and Eastal 1986; Pierce et al., 1987). Larvae seek to attract ants by secreting sugary and nutritious exudates highly appreciated by ants, through exocrine glands - myrmecophilous organs - first described by Newcomer (1912). Lenz (1917) proposed another interpretation of the origin of these exudates, as adaptation of Lepidoptera larvae to produce a sugary liquid to prevent aggression by ants. In this case, any effect those ants have in protecting the caterpillars would be a secondary consequence, but equally effective. In addition, caterpillars and pupae of myrmecophilous Lycaenidae can use acoustic signals (stridulatory organs) to attract the ants (Pierce, 1995; Pirce et al., 2002). Recently, in Álvarez et al. (2012, 2014) the stridulatory organs are found in myrmecophilous and nonmyrmecophilous lycaenids that supported the idea that sound production is not necessarily related with myrmecophily within the Lycaenidae. Commensalism that becomes a mutualistic relationship is a common process in the evolution of many interactions (Margalef, 1974). But in some cases the larvae of certain butterfly species exploit ant nests as food resource and shelter, and behave as specialized social parasites (Witek et al., 2008). In the genus Phengaris Doherty, 1891 some species prey on ant brood and are called predatory species, while others, termed “cuckoo” species, mimic ant larvae and are fed directly by workers (Witek et al., 2008). Whatever the origin may be, the caterpillars are at least to some extent protected through the presence of ants from predators and parasitoids (Fiedler et al., 1993; Jordano et al., 1992.), although some parasitoids have successfully specialized on Lycaenidae and may inflict heavy mortality (Bink, 1970, Shaw, 1996, Shaw et al., 2009), and some extraordinary associations and behaviors have resulted (Thomas and Elmes, 1993; Thomas et al., 2002). Thus many Lycaenidae have associations with ants, which can be both facultative and obligatory, ranging from mutualism to parasitism (Pierce et al., 2002). As a result, more than half the species of the family Lycaenidae may have an association with ants at some stage of their development (Pierce, 1987; Fiedler, 1996, 2006).

For many of the Iberian Lycaenidae, interactions with ants constitute a facultative and slack mutualism and, therefore, this association is not strictly necessary for the full development of the larva. Just in a few species, such as Plebejus argus (Linnaeus, 1758) (Thomas, 1985; Seymour et al., 2003), an obligate myrmecophily occurs and, in the most extreme case, mutualism becomes obligate parasitism, as in genus Phengaris, regarded as social parasitism (Thomas et al., 1991; Munguira and Martín, 1997; Als et al., 2001; Witek et al., 2008.).

Species Assocations
Phengaris (=Maculinea) (Lycaenidae) - Sielezniew et al. (2015) - Caterpillars develop on specific host plants (depending on species: Thymus or Origanum, Gentiana and Sanguisorba) and complete their development inside the nests of specific red ants (Myrmica sp.) as social parasites feeding on the hosts’ brood, or being fed by trophallaxis (Thomas, 1995).