Malvaceae, in Central Europe usually Malva moschata and M. alcea, in the South often Malva neglegta or Althaea.
Carcharodus alceae colonizes dry warm open areas with the larval host plants such as calcareous grasslands, ruderal areas, road side verges, flood embankments and quarries. In Southern Europe Carcharodus alceae is a ubiquist, which reproduces also in urban areas. This species spreads in Central Europe in the course of global warming and an increasement of Malvaceae in gardens and along roads.
There are several generations per year. In Central Europe Carcharodus alceae usually occurs in two generations with butterflies from late April to June and again from mid-July to early September. In the south there are mostly at least three generations in lower elevations.
The caterpillar overwinters in most cases mature and pupates in the spring without re-feeding. After late oviposition (i.e. in late August and September), I observed, however, also hibernation in penultimate instar or younger. Moreover I observed feeding mature larvae in April in Provence (Alpilles, 2013).
In Central Europe this species is threatened by the disappearance of extensively managed grasslands, ruderal areas (overbuilding!) and wrong, because to intensive mowing of road side verges and flood embankments around the Rhine.
In recent years (2010 and 2011), for example in the Swabian Alb - but also elsewhere - you can observe an increasement probably due to climate warming and the spread of hollyhocks on roadsides. So I found caterpillars on the southwestern Swabian Alb near Veringendorf (Germany) and on the eastern Swabian Alb near Dischingen and Neresheim in 2011. In both locations these were the first observations.
Carcharodus alceae is distributed from Southern Spain across Southern and Central Europe to North India and China.