Hydrogen-cyanide
Guides
Apheloria montana
mountain cherry millipede
Apheloria montana is a large flat-backed millipede in the family Xystodesmidae, native to the southern Appalachian Mountains of eastern Tennessee and western North Carolina. It serves as the type species for the genus Apheloria. The species produces hydrogen cyanide and benzaldehyde as chemical defenses, which emit a characteristic cherry or almond odor. Its bright yellow or orange spots function as aposematic coloration warning predators of its toxicity.
Apheloria virginiensis corrugata
Aromatic Cherry Millipede
Apheloria virginiensis corrugata is a subspecies of flat-backed millipede in the family Xystodesmidae, commonly known as the Aromatic Cherry Millipede. Like other members of the genus Apheloria, it produces hydrogen cyanide (HCN) as a chemical defense and displays bright aposematic coloration warning predators of its toxicity. The species exhibits the characteristic flattened body shape of Polydesmida, with lateral expansions of the dorsal segments called paranota. It belongs to a group of xystodesmid millipedes that share warning coloration patterns across related genera including Apheloria, Boraria, and Cherokia.
Boraria infesta
Boraria infesta is a species of flat-backed millipede in the family Xystodesmidae, native to southeastern North America. It belongs to a group of polydesmidan millipedes that produce hydrogen cyanide as a chemical defense and display aposematic coloration warning predators of their toxicity. The species is part of a genus closely related to other cyanide-producing millipedes including Apheloria and Pleuroloma.
Cherokia georgiana georgiana
Cherokia georgiana georgiana is a millipede subspecies in the family Xystodesmidae, characterized by its black body with yellow wedge-shaped posterolateral markings and a wrinkled dorsal surface. It belongs to the order Polydesmida, a group distinguished by lateral expansions of dorsal segments into "paranota" that give a flattened appearance. Like other members of its genus and related genera, it produces hydrogen cyanide (HCN) as a chemical defense against predators, with its bright coloration serving as aposematic warning signals.
Harpaphe haydeniana
yellow-spotted millipede, almond-scented millipede, cyanide millipede
Harpaphe haydeniana is a flat-backed millipede native to the Pacific coast of North America, recognized by its black body with yellow-tipped lateral keels. The species is notable for its chemical defense system, secreting hydrogen cyanide when threatened, which produces a characteristic almond odor. It plays a significant role in forest decomposition, particularly in redwood ecosystems. Despite its common names suggesting uniqueness, both the color pattern and cyanide defense occur in other flat-backed millipedes globally.
Harrisina
grapeleaf skeletonizer moths
Harrisina is a genus of moths in the family Zygaenidae, commonly known as grapeleaf skeletonizer moths. The genus includes several species, notably Harrisina americana (grapeleaf skeletonizer) and Harrisina metallica (western grapeleaf skeletonizer), which are significant agricultural pests of grapevines. Members of this genus are characterized by their aposematic coloration—typically black with bright red or metallic markings—and their ability to produce hydrogen cyanide as a chemical defense. The larvae feed gregariously on grape foliage, skeletonizing leaves by consuming the tissue between the veins.
Harrisina americana
Grapeleaf Skeletonizer Moth
Harrisina americana, commonly known as the Grapeleaf Skeletonizer Moth, is a day-flying moth in the family Zygaenidae. Adults are uniformly black with a distinctive bright red collar on the neck, serving as aposematic warning coloration. The species is notable among insects for its ability to produce hydrogen cyanide as a chemical defense. Larvae feed on grape family plants, skeletonizing leaves by consuming tissue between the veins. The moth is widespread in the eastern United States and is frequently observed in association with wild and cultivated grapes as well as Virginia creeper.
Promecognathus
Promecognathus is a genus of ground beetles comprising two described species, P. laevissimus and P. crassus. These beetles are specialist predators of cyanide-producing flat-backed millipedes in the family Xystodesmidae. They possess exceptional physiological tolerance to hydrogen cyanide, surviving doses 7–15 times greater than those lethal to other carabid beetles. This tolerance allows them to attack millipedes directly without behavioral avoidance of chemical defenses, representing the first documented case of cyanide tolerance in predatory insects.
Pyromorpha
orange-patched smoky moths, leaf-skeletonizer moths
Pyromorpha is a genus of zygaenid moths known as leaf-skeletonizer moths. Species in this genus possess aposematic black and orange coloration and contain hydrogen cyanide at all life stages, which they synthesize rather than sequester from host plants. The genus participates in Müllerian mimicry complexes with net-winged beetles (family Lycidae), particularly Calopteron terminale. At least one species, P. dimidiata, has larvae that feed on leaf litter, especially oak leaves.
Pyromorpha dimidiata
Orange-patched Smoky Moth
Pyromorpha dimidiata is a leaf skeletonizer moth in the family Zygaenidae, native to eastern North America. Adults display distinctive orange and dark gray forewings with a pattern that resembles toxic net-winged beetles (Calopteron spp.) in a Müllerian mimicry complex. All life stages contain hydrogen cyanide, which the moth synthesizes independently rather than sequestering from host plants. The species is active primarily in spring and early summer.
Semijulistus flavipes
Semijulistus flavipes is a flat-backed millipede in the family Xystodesmidae, order Polydesmida. The species was formerly classified under the genus Pleuroloma, and taxonomic revisions have placed it in Semijulistus. Like other xystodesmid millipedes, it produces hydrogen cyanide (HCN) as a chemical defense. The specific epithet "flavipes" refers to yellow leg coloration.
Zygaenidae
burnet moths, forester moths, smoky moths, leaf skeletonizer moths
Zygaenidae is a family of approximately 1,000 species of diurnal moths in the superfamily Zygaenoidea. Adults are characterized by metallic coloration, often with red or yellow spots, and clubbed antennae. Members of this family are notable for their ability to produce and sequester hydrogen cyanide as a chemical defense throughout all life stages, making them among the few insects capable of synthesizing this toxin independently of dietary sources. The family includes seven subfamilies, with Zygaeninae (burnet moths) and Procridinae (forester moths) being the most frequently encountered in temperate regions, while Chalcosiinae dominates tropical faunas.