Butterflies of the Amazon and Andes
Dyson's Blue Doctor
Rhetus dysonii  SAUNDERS, 1849
subfamily - RIODININAE
Rhetus dysonii male, Antioquoia, Colombia  Adrian Hoskins
Butterflies in the genus Rhetus are noted for their short palpi, and for having a beautiful blue sheen across the upper surface of the wings. Rhetus are closely allied to Ancyluris and have a very similar wing shape. In Ancyluris however there is a blue iridescence on the underside of the wings, but not on the upperside.
There are 3 Rhetus species, of which periander is the commonest and most widespread. The others are arcius which is paler, with longer thinner tails; and the species featured here - dysonii, in which the pink markings on the hindwings are of a different configuration. Only males have the metallic blue scales - females are banded with pure white.
Rhetus dysonii occurs in Panama, Colombia, Ecuador, Peru, Brazil and Bolivia.
Rhetus dysonii caligosus female, Tatama NP, Colombia  Adrian Hoskins
This species is usually found singly, in association with narrow streams or ditches, often in disturbed areas such as roadsides or forest glades. In Central America it occurs at elevations between about 1000-1500m. In the eastern Andes the altitudinal range is greater, from about 800-2000m.
Rhetus dysonii caligosus Medellin, Colombia  Adrian Hoskins
I have no information regardinmg the larval foodplants. The eggs of other Rhetus species are white, and laid singly on stems or leaf axils.
Rhetus dysonii male, Rio Kosnipata, Peru  Adrian Hoskins
Adult behaviour

The butterflies are mainly active in the afternoon and are seen more frequently in cloudy conditions or in dappled sunlight, than in bright sunshine. They are nearly always found close to small streams or ditches, where they imbibe dissolved minerals from the mud. At such times are very placid and not easily disturbed.

Rhetus dysonii caligosus female, Tatama NP, Colombia  Adrian Hoskins



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