It belongs to a genus which is found throughout the whole Holomediterranean and central Asiatic area, from the Atlantic to the Himalayas and encompassing about 9 species. They are all rather secretive and local species in scrubland or rocky xeric habitats and aren't well known by most people because they fly so early in the year.
Male Tomares ballus
For instance, Tomares ballus can be seen on the wing as early in the season as late December in Morocco until mid March although it's normal flight period goes from late February to mid April, depending on weather, altitude and sun exposure.
Female Tomares ballus, a bit more colourful than the male
In Portugal this species is found sparsely and it's distribution is not very well known because of its early flight period. There are colonies known from pretty much the whole of the country although it seems to prefer xerothermophilous situations in rather mesic habitats (clearings, calcareous hills) in the western and southern part of the country and colonies are very local with a small number of individuals.
Typical habitat, mediterranean scrubland covered xerothermophilous hills.
Females are more commonly seen and both sexes can be usually flushed out of the most usual foodplant, Astragalus lusitanicus (Erophaca baetica).
Footplant: Astragalus lusitanicus (Fabaceae), forming characteristic clutches.
This is quite a difficult species to photograph as the butterflies are rather wary and tend to land in difficult positions for the photographer, among grasses and the foodplant, so one needs to be (very!) patient.
Female Tomares ballus on A. lusitanicus. (Near the centre of the picture)
