Six-spot burnet moths are normally found in meadows, grassland, and along the coast - but this population has taken up residence in the meadows next to a motorway.
This short film looks at the six-spot burnet's brief adult lifecycle, with tales about toxic gifts during sex, and ghostly skins left behind when they reach adulthood.
The side of a busy motorway services near Glasgow is not where you’d expect to find a wildlife haven; but in this urban meadow, you can find a healthy population of six-spot burnet moths.
The adult six-spot burnet’s lifecycle may be brief at only a month or so, but it is quite an extraordinary tale – with toxic gifts during sex, and ghostly skins left behind when they reach adulthood.
Six-spot burnet moths are striking in their colouration and patterning, which makes them easily recognisable: their shiny black – almost metallic – long, thin wings, and characteristic six red spots help them stand out from the soft browns and yellows of the meadow.
This kind of patterning is often referred to as “warning colouration”, as six-spot burnet moths produce the toxic chemical hydrogen cyanide. This gives the moths a bad taste, and – in large quantities – will kill predators; helping to protect the moths throughout their lives.
Hydrogen cyanide also plays an important role in the moths’ sexual reproduction: females will release plumes of the chemical, combined with sexual pheromones, to attract males. During reproduction, male moths will present females with a nuptial gift – a type of nutritional gift sometimes given by the male, to induce the female to mate with him. In this case, he presents her with hydrogen cyanide. The female can then use this toxic gift to provide her offspring with more hydrogen cyanide, so they will be better protected against predators when they emerge.
These ghostly white tents with alien-like creatures emerging from them are actually the cocoons and abandoned exuviae of young six-spot burnet moths. The moths emerge from this exoskeleton after pupating, and fly away to feed and find a mate – leaving this shiny black case behind.
The adult moths are day-flying, and feed on the nectar of knapweed, thistle, and other grassland and meadow flowers. This moth is looking a bit bedraggled, and may have already mated – the female moths will lay their eggs on the caterpillars’ foodplants, bird’s-foot trefoil, before dying around June or July.
It is quite amazing to be able to find these moths in such an urban landscape – so keep an eye out for these astonishing, flamboyant little moths around your local patch.
REFERENCES AND WIDER READING
Butterfly Conservation (2021) Six-spot burnet moth, Available: https://butterfly-conservation.org/moths/six-spot-burnet [Accessed: 18/07/2021]
Gomez A. (2011) Six-spot burnets: chemical weapons as nuptial gifts, Available: http://abugblog.blogspot.com/2011/07/six-spot-burnets-chemical-weapons-as.html [Accessed: 18/07/2021]
Morris T. (2009) Six Spot Burnet Moth, Available: https://www.islay.blog/article.php/six-spot-burnet-moth [Accessed: 18/07/2021]
Pavid K. (2016) Toxic talents of Britain’s cyanide moths, Available: https://www.nhm.ac.uk/discover/toxic-talents-cyanide-moths.html [Accessed: 18/07/2021]
The Wildlife Trusts (2021) Six-spot burnet moth, Available: https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/moths/six-spot-burnet-moth [Accessed: 18/07/2021]