Pyrgus onopordi (Rambur, 1839)

Host plants:
In Provence, the caterpillars live on Potentilla hirta and P. pusilla (Nel 1985 and own observations), but probably also to P. reptans. In Valais, it was found, according to literature, on Helianthemum nummularium. In breeding, the caterpillars accept both genera as do those of P. cirsii, P. armoricanus and P. carlinae, so this seemed plausible. In the end of June 2008, I observed then in the Sierra Nevada and adjacent mountains (Southern Spain) oviposition on Potentilla reptans, Helianthemum apenninum and Malva neglecta. The use of hollyhocks in European Pyrgus species had previously been referenced always in the realm of fables, in most cases rightly. Pyrgus onopordi seems to constitute a prominent exception. In North America, a number of Pyrgus species lives on Malvaceae according to literature.

Habitat:
Pyrgus onopordi colonizes hot rocky slopes, grasslands and dry ruderal terrain. In Provence, the butterflies love living on the edge of dry, partly wooded ravines at the foot dry, bushy slopes. In the northern part of the distribution Pyrgus onopordi is restricted to lower altitudes up to 1400m above sea level. In the Sierra Nevada, I met ovipositing females still over 2500m above sea level on xerothermic pastures on Malva neglecta.

Life cycle:
The life cycle is similar to Pyrgus armoricanus. The adults appear in one to three generations per year. This already shows that the tendency to development without hibernation is not quite as pronounced as in Pyrgus armoricanus. In July 2005 I observed several half-grown caterpillars together with fresh adults of the partial second generation (Provence, app. 700m above sea level). These caterpillars did not develope until after hibernation in spite of increased temperatures (in rearing). This may be an adaptation to summer drought. The caterpillar overwinters as L4, after late oviposition, however, in a younger instar from L1 onwards.

In the Spanish Sierra Nevada I observed many mostly fresh adults up to over 2500m above sea level in the end of June 2008 which belonged to the first or second genaration according to the elevation of the location. A clear separation is not possible in such regions.

Endangerment factors:
In Germany only two historical observations are known from the Swabian Alb (Ebert & Rennwald 1989). For this demanding species (microclimate!) hardly exist any potential habitats in Central Europe today.

Remarks:
It is a southwestern species (Northwest Africa to Italy) with relict populations in the Valais. In the mountains of Southern Spain Pyrgus onopordi is still the most common Pyrgus.

Hints on determination:
The adults are often slightly yellowish scaled. The most important distinguishing mark is the anvil-like white spot on the hindwing lower side. But this can exceptionally be also the case with Pyrgus armoricanus and other species. As a result Pyrgus onopordi can easily be confused with other species without experience and/or genital section.