Sideridis rivularis (Fabricius, 1775)

Host plants:
The species lives on flowers and fruits, later also leaves, of Caryophyllaceae species, especially Silene vulgaris. In addition, I found caterpillars in Silene dioica, Saponaria officinalis and Lychnis flos-cuculi.

Habitat:
Sideridis rivularis colonizes various, but mostly rather mesophilic habitats. I found caterpillars on meadow edges, mountain pastures, in the Pinus mugo-belt at about 1700m above sea level, on calcareous grasslands, along forest paths, in fens and other little mown sites of larval food plant. In Schwäbisch Gmünd (Southern Germany) they populated two years after sowing a meager embankment beside a main road where Silene vulgaris occurs. But Sideridis rivularis avoids extremely hot and dry places at least in summer and occurs there more at mesophilic edges.
Sideridis rivularis can beconsidered as highly mobile, because it colonizes new pinks occurrences quite fast. But this may correlate with the still quite good population density.

Life cycle:
Sideridis rivularis is polyvoltin and has often three generations in the lowlands, but in cool summers or medium-high altitudes only 2 generations. The caterpillars are found from early May to late October, with a peak from mid-June to mid-July and again from mid-August until the autumn. In the Alps, the caterpillars are observed in a single generation from 1500m asl upwards, especially in July and August. The eggs are deposited on the flowers and flower buds. Some own field observations took place on the calyx outer side of buds, which differs from the Hadena species that oviposit only inside the flowers. But probably Sideridis rivularis lays partly into the flowers, too. The young caterpillars feed on the developing seeds. Later, leaves are also consumed. The older caterpillars hide during the day partly on the ground and partly in the calyx.

Endangerment factors:
Sideridis rivularis is besides Hadena bicruris the most widespread species and not seriously endangered, but surely in decline in the lowlands due to intense agriculture etc.

Remarks:
The total distribution ranges from Northern Spain across most of Europe (missing only in the extreme south) to China.