Cupido argiades (Pallas, 1771)

Host plants:
The eggs are deposited on flowers and buds of Fabaceae. Most important are Trifolium pratense, Lotus corniculatus and Lotus uliginosus. In addition, the literature also mentions Medicago, Coronilla and Astragalus.

Habitat:
Cupido argiades inhabits particularly extensive wet meadows, fens and wet fallow land. In addition, it is also found in woodland clearings, on dams and occasionally also in drier grasslands.

Life cycle:
Cupido argiades has between two and four generations per year. In southwestern Germany there are usually three (April/May, mid-June to early August and late August to September). The mature caterpillar overwinters as praepupa (takes no more food in the spring). I met eggs and caterpillars, which live freely in the flower heads, several times from July to September on Trifolium pratense and Lotus. Often the detection of eggs and caterpillars is much more effective than that of the butterfly. For that a sample of the flowering shoots in the right phenological state (just faded) should be collected (the plants are not endangered), suitably stored and shaken out several times after a few days. The caterpillars are easily distinguished from those of Polyommatus semiargus and P. icarus. Also, the eggs can be searched with quick success at the site, so that the method of detection of the larvae is recommended only if you have to seek in the phenological hole between generations.

Endangerment: endangered

Endangerment factors:
Cupido argiades is endangered due to the decline of extensive wetlands and was already strongly suppressed in the Upper Rhine Valley until the early 1990s. The increasingly manifesting global warming has since that brought a boom to the polyvoltine, mobile species. So they could already spread eastward to Bavaria. 2010, she has also reached Schwäbisch Gmünd. Whether it goes up also to the Swabian Alb remains to be seen.

It is now found also on the Upper Rhine in many additional habitats, such as even in completely overgrown clearings (with neophytes like Solidago canadensis). However, I think is in spite not unthreatened because the primary key habitats have almost disappeared (species-rich and extensive wet meadows) and already a perennial cool weather could wipe out many new populations again.

Remarks:
The total distribution ranges from Northern Spain across central and Eastern Europe and temperate Asia to Japan. In Germany it is focused mainly in the catchment area of the Upper Rhine (Baden-Württemberg, Rhineland-Palatinate), but has spread in recent years as portrayed strongly.