Six-Spot Burnet Moth

Zygaena filipendulae — the six-spot burnet moth — is one of the most chemically interesting moths in Europe and one of the few insects that produces and stores genuine HYDROGEN CYANIDE as defensive chemistry. Adults are 35-40 mm wingspan with iridescent blue-black forewings carrying six bright red spots (the source of the species' common name) and entirely red hindwings — bright aposematic warning coloration that signals to bird predators that the moth is genuinely toxic. The chemistry behind the warning is unusual: caterpillars feed on bird's-foot trefoil (Lotus corniculatus) and other Fabaceae host plants that contain cyanogenic glycosides — primarily linamarin and lotaustralin. The caterpillars sequester these compounds, store them in cuticular reservoirs, and pass them through metamorphosis to adults. Adults additionally synthesize MORE cyanogenic glycosides de novo from amino acids — the species is one of very few insects known to produce cyanide compounds endogenously rather than only acquiring them from food. When threatened by a bird predator, adult burnet moths exude visible droplets of the cyanogenic compounds from cuticular pores; these droplets release hydrogen cyanide gas on contact with the predator's tissues, causing immediate respiratory distress and bitter aversive taste. Birds that attempt to eat a burnet moth typically reject it within seconds and learn to avoid the species permanently. The species is the textbook example of insect cyanogenesis (cyanide production) and is featured in major chemical ecology research programs at the University of Copenhagen (Møller lab) and Aarhus University. The species also has a remarkable life history: caterpillars overwinter, pupate in distinctive yellow papery cocoons attached to grass stems, and emerge as adults in late June through August. Burnet moths are diurnal (day-flying) — one of the few moth groups that has fully transitioned from nocturnal to diurnal activity, supported by their chemical defense (which makes daytime flight safer than for cryptically-colored nocturnal moths).