Species of the week # 97 – purple-barred yellow

Brandenburg’s butterfly researchers could hardly believe their luck in 2003. In the heatwave summer, in which man and nature everywhere had a hard time, there was a wonderful surprise. The purple – barred yellow moth, which had been lost for years, suddenly reappeared in large numbers; even in areas where it had not appeared for decades.

Distribution status in Rhineland-Palatinate Extinct
Remaining occurance Saxony, Brandenburg, Southern Europe
Last sighting in Rhineland-Palatinate unknown
Habitat Sandy grasslands, warm stony slopes
Threat Habitat loss due to over-fertilisation and building development

The researchers found that a complete third generation of purple-barred yellows had developed this year, which otherwise happens very rarely north of the Alps. Because purple-barred yellows like to undertake so-called dispersal flights, i.e. leave their actual habitat to explore new areas, they could be sighted in new and unusual places. The butterfly with the ochre forewings and the two purple cross-lines needs two things in its habitat: firstly, there must be a lot of knotweed plants, the only food for its caterpillars, and secondly, the area must be sunny and dry, even windy. The purple-barred yellow does not like moisture at all. Its usual habitats are therefore on the sunny side of country lanes, windmills and even on heavily destroyed, drained moors. This is because the sun heats up the black bog soil particularly well here.

In Baden-Württemberg, where the species used to be more widespread in the warm Upper Rhine Graben, probably the last occurrence was destroyed by development in 2003.

Due to the decline of sandy grasslands and extensive, dry fields caused by overfertilisation, the purple-barred yellow is finding less and less suitable habitat. Climate change seems to give it a survival advantage in some years, but whether this will benefit it in the long term is highly doubtful.

Politically necessary:

– Stop overfertilisation

– Reduction of land consumption

– Protection of fallow land and wasteland

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Photo: By Katya from Moscow, Russia – Пяденица пурпурная / Lythria purpuraria / Purple-barred Yellow / Knotweed Purple Moth, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=45503987