Six-spot burnet moth: structural iridescence and aposematism

Six-spot burnet moth, Zygena filipendulae, on scabious

Red and black spells danger, the six-spot burnet moth is aposematic with colours to warn-off a predator. Beware toxins, from caterpillar to moth this species can produce hydrogen cyanide. 
In distinctive buzzing flight the day-flying six spot burnet moth gives glimpses of red and black.  Settled to nectar on scabious,  its fore-wings show  black with red spots.  I've seen moths mating,  together on scabious for well over an hour, so warning colours could help protect them when they're vulnerable to predation.
Wings closed as the moth nectars on a flower, that's the classic field-guide look. Wings open, the hind-wings are bright red with a dark margin.  It's a striking moth.
Six-spot burnet moth, Zygena filipendula. A blog of mid-summer's day 2018 (see link below) shows six-spot burnet, Zygena filipendula, on Dropwort, Filipendula vulgaris which is another flower favoured by the moth when it seeks nectar.  
             Six-spot Burnet Moth 

Out on the limestone grasslands of Scout Scar photographing six-spot burnet I watch a moth seeking nectar on yellow hawkweed, interacting with the flower, changing position.  I'm circling the flower,  watching how sunlight falls upon the moth in fresh angles of incidence, seeing its wings assume sheen and iridescence,  seeing colours modify each moment.  

 With wings closed the moth's black fore-wings may suddenly assume a soft, silvery sheen.  Its clubbed antennae may show blue, as on mid-summer's day 2018. The incidence of light is transient,  as the moth moves, as sunlight strikes it and structural iridescence comes into play, so  colours are constantly modified. Moths and butterflies can confuse predators in this way. On the yellow hawkweed, one red hind-wing appears momentarily orange,  the wing is translucent and yellow petals show through.   Sunlight and shadow also affect how we see moths and butterflies.  I find it fascinating, and beautiful to see the effects of structural iridescence.
For structural iridescence and  Britain's cyanide moths - see link to The Natural HIstory Museum

Toxic talents of Britain's cyanide moths
Natural History Museum
https://www.nhm.ac.uk › discover › toxic-talents-cya
Natual History Museum
Natural Hisory Museu