Zygaena purpuralis (Brünnich, 1763)

Host plants:
Thymus species

Habitat:
Zygaena purpuralis inhabits especially nutrient-poor grasslands, heathlands, sometimes also calcareous fens with thyme in drier areas (hummocks), mountain slopes and pastures (in the northern Alps only relative rarely in highr elevations, otherwise up to 2500m). It still occurs in almost all reasonably intact nutrient-poor grasslands of the Swabian Alb, even if abundances seem to decrease due to the increasement of grasses and other vegetation due to less frequent grazing and other factors.

Life cycle:
The caterpillar overwinters smaller than that of Z. minos on the eastern Swabian Alb, resumes activity a little later in the spring and therefore Zygaena purpuralis flies mainly in July and August. In other areas, the situation may be different. At Mount Olympus in Greece, I observed adults in the spring (May) in around 1000m above sea level. In lower altitudes of the Swiss Valais the main flight time is also earlier between June and early July. Larvae hibernate larger there than in the eastern Swabian Alb. As it is the case with its congeners, the larvae may hibernate several times. The cocoon is constructed on the soil in moss etc.

Selection factors such as the phenology of the resources (nectar plants) also play a great role.

Endangerment factors:
The risk is slightly lower than in Zygaena minos because of the smaller requests on habitat quality and microclimate. But Thymus needs grazing, except for rocky slopes. Thus even this formerly widespread species is becoming more and more scarce in many regions.

Remarks:
Zygaena purpuralis is distributed from France and Great Britain to the Tien Shan. Unlike Zygaena minos it occurs up to more than 2300m above sea level in the Alps.