species of the week #62 – rock grayling

The rock grayling is almost invisible in its habitat. With its irregular brown colouring, it is perfectly camouflaged in sandy pine and oak forests. Moreover, it is often confused with its big brother, the woodland grayling. The two moths can only be distinguished from each other under a magnifying glass. Both have special scent scales to attract other moths. The rock grayling, however, only needs six scent sticks, whereas the woodland grayling spreads a whole cloud of scent with up to 30 sticks. However, any confusion is not serious, after all, the woodland grayling is also on the Red List of Threatened Species.

Distribution status Threatened with extinction
Remaining deposits Hunsrück, Saxony, Brandenburg, Central Europe
Last sightning in rhineland-palatinate 2009 in Kaub
Habitat Light, dry sandy pine forests, dry grasslands, heaths
Threat Biotope fragmentation, intensive forestry, loss of biotopes at forest edges

The moths show the greatest activity in the morning and late afternoon hours, while on hot days they rest on half-shaded pine trunks during midday. They also seek these out for the night. For sunbathing, the moths need free, preferably wind-protected places, which they find on tree trunks as well as on free sandy surfaces.
Because the butterfly often commutes between resting places in the forest and the flowering plants of the adjacent forest fringes, it has been imaginatively named forest porter (Waldportier) in german. When it comes to food selection, the butterflies prefer blue or purple flowering plants such as mountain sand button and sand thyme.
The last stable populations of the rock grayling are concentrated in Saxony and Brandenburg in the post-lignite open-cast mining landscapes in Lusatia. These populations in Lusatia can exist because individual sunny areas and forest margins were created in the otherwise closed pine forests by electricity, gas or railway lines, but the forests were kept free from development, agriculture and trunk roads as production areas of the mining industry.
In Hunsrück, the rock grayling is very rarely seen, while in the Upper Rhine and Nahe valleys it has already become extinct or disappeared. The last record comes from Kaub and dates back twelve years.

Politically necessary:

  • Extensive forest management especially in extreme locations
  • Mosaic-like biotope network
  • Securing undissected forest and biotope areas

Photo: By Natuurbeleven – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=71188617

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