1. Geographic variation in the male genitalia of Carcharodus alceae (Esper) Carcharodus alceae is widespread in the Palaearctic region: it occurs from the Sahara to Northern Germany and from Portugal to the Altai, Turkestan and Kashmir, from where it penetrates the Oriental region along the southside of the Himalayas to Mussoree; isolated from its main range it occurs in Southwestern Arabia. Although it is a species of dry and warm localities, such as steppes, sunny slopes, dry meadows, etc., even flying in the semidesert in Morocco, it ascends to 1600 m in the Alps (Kauffmann, 1951). The large range of temperatures thus covered by alceae is reflected by the variation in number of broods per year. In the mountains and north of the Alps there are one or two broods, south of the Alps three or four. In the Near East alceae is on the wing from the beginning of February to the end of November (Ellison & Wiltshire, 1939; Wiltshire, 1957). But alceae does not react to ecological differences by varying in the number of broods per year only, it is also variable in size and colouring. As ecological factors such as temperature and humidity are largely geographically distributed, there appears to be a marked geographic variation. This has led to the description of many "subspecies" that are actually climatic or seasonal forms. As undoubtedly a part of the geographic variation of alceae in size and colour is due to geographic isolations during the Ice Age, the study of the geographic variation of this species is very complex. As far as known the genitalia usually do not react to ecological changes to the same extent as size and colour; normally there is no reaction at all. If there is a geographic variation in the genitalia, this can usually be explained as a