Association of caterpillars of Blues and Hairstreaks (Lycaenidae) with ants range from absent to facultative (opportunistic) to obligate (compulsory), and from mutualistic to parasitic. At one end of the spectrum, caterpillars of species such as the Red Pierrot (Talicada nyseus; left) do not associate with ants directly, but are also not attacked by them as are most caterpillars. They have thick larval skins or cuticles characteristic of many lycaenid caterpillars, and appear to retain pore cupolae organs, but all other ant associated structures develop only to a rudimentary state. Caterpillars of facultative associates such as the Common Cerulean (Jamides celeno; centre) live with ants whenever they find the right ant species, but they are also fine without ants. In these species, the ant-associated organs are developed reasonably. At the other extreme, caterpillars of species such as the Lilac Silverline (Apharitis lilacinus, right) are obligate associates of ants, in which the ant-associated organs are remarkably developed. Females of such obligate associates lay eggs very close to ant nests. Caterpillars and pupae are constantly attended by ants, and they may live inside ant nests, often among the brood of ants. In some of these species, caterpillars do not feed on plants at all. Instead, they eat food regurgitated by the tending ants. In a rare turn of events, the caterpillars of some species may also slyly eat the ant brood, turning this association a bit sinister.