Aescelin in the bark and leaves of the local vadgesztenye fák (horse chestnut trees) shows colour in wavelengths invisible to the human eye,  in the range of 10 to 400 nm. I detected its presence through the secondary blue fluorescence of a twig from the tree in a jar of Danube water under ultra violet light.

These high frequencies are visible to some insects and I wonder if it’s a ‘welcome’ to the cameraria ohridella moth, which has its own unique and strange attraction to the horse chestnut tree.