Eurybia elvina

As in all butterflies, E. elvina are holometabolous and have four distinct development stages: egg, larva, pupa and adult. It takes a total of 45 days for an adult to eclose from an egg. Egg The females lay the eggs on the upper surface of leaves, leaf petioles, or on the inflorescence of neotropical plants such as Calathea ovandensis. The eggs are not laid in a clutch, but are generally isolated. Sometimes, however, they may be found in widely spaced groups of five or fewer eggs. It takes, on average, 3 days for the first instar of larva to hatch out of the egg. First instar The first instar emerges from the egg by chewing through the micropyle. The body of the caterpillar is pale-yellow in color with a black head capsule. This coloration acts as a camouflage against the corolla of the host plant (Calathea spp.) on which the caterpillars are found. They feed on all parts of the flower and grow from a length of 1.5 mm to 4.5 mm. The dorsal setae of this instar are much longer than those of the other instars. The first instar period lasts for an average of 4.5 days. The adults drink floral nectar from the host plants. The host plants are typically members of the genus Calathea and Ischnosiphon pruniosus. == Pollination ==

The long proboscis of the adult does not touch the stigma or the pollen of the plant while feeding on C. ovandensis. Thus, they never pollinate the host flowers. Such visits are expected to be detrimental for plant reproduction, as the loss of nectar reduces the plants' success of pollination during future visits. This may also lead to tripping of flowers with no pollen exchange, resulting in reduced fruit-set. However, it has been observed that Eurybia elvina rarely trip flowers. It was found that their ineffective pollination in the study system did not significantly reduce fruit-set. Thus, the adult interaction with the host plant is commensal. ==Mutualism with ants==

The larval stages of E. elvina have been found in mutualistic associations with several ant species, such as the electric ant, Brachymyrmex musculus, Paratrechina spp. and fire ants among others. This type of an association is generally referred to as myrmecophily. The tentacle nectary organ (TNO) found that the eighth abdominal segment of the larval stages plays a special role in this interaction. This organ secretes exudates rich in sugars and amino acids which is harvested by the ants. This secretion has been found to be biochemically similar to the nectar produced by the host plant (C. ovandensis). The later instars of the caterpillar position themselves in the inflorescence such that the TNO is presented to the ants at roughly the same level of the nectaries of the flower. Some species of ants build soil shelters around the later instars on the inflorescences. The pupal stages were also attended by ants even though they produce no exudates. It is thought that the association with ants may protect the caterpillar from enemies. == Physiology ==

Sound production A number of riodinid species are known to produce audible signals using epicranial granulations. An experiment to see if this behavior exists in E. elvina was conducted in Soberania National Park, Panama using E. elvina caterpillars and the ant species Ectatomma ruidum. The caterpillar was observed producing 12–15 pulses of sound per second when walking and foraging, either when alone or when accompanied by E. ruidum ants. As they produced sound, the caterpillars oscillated their head laterally, and the sound stopped when the oscillations ceased or when the head region was not in contact with the substrate (branch). The investigators of the experiment were able to discern that E. elvina caterpillars produce sound by oscillating their head in order to scrape the teeth that cover their cervical membrane against the epicranial granulations located on the surface of their heads. == References ==