Chemical-defense
Guides
Abacion magnum
crested millipede
Abacion magnum is a crested millipede species in the family Abacionidae, first described by Loomis in 1943. It is native to North America and is characterized by defensive chemical secretions containing p-cresol. In captivity, it has been observed to feed on dead insects and conspecifics, indicating opportunistic scavenging behavior.
Adalia
ladybugs, lady beetles, ladybirds
Adalia is a genus of lady beetles (Coccinellidae) containing two species: A. bipunctata (two-spot ladybird) and A. decempunctata (ten-spot ladybird). These beetles are aphid predators found across the Palearctic region. Both species exhibit color pattern polymorphism and possess alkaloid chemical defenses. A. bipunctata is known to harbor multiple male-killing symbionts including Wolbachia, Rickettsia, and Spiroplasma, though symbiont phenotypes vary geographically.
Adephaga
Ground and Water Beetles, adephagans
Adephaga is the second-largest suborder of beetles, comprising over 40,000 species across 10 families. The suborder includes ground beetles (Carabidae), tiger beetles, predaceous diving beetles, and whirligig beetles. Members are characterized by specialized anatomical features including visible notopleural sutures and a first abdominal sternum separated by hind coxae. The vast majority of species belong to the family Carabidae.
Agraulis
Agraulis is a subgenus of longwing butterflies (Heliconiinae) within the genus Dione. The group contains at least two species: the widespread Gulf fritillary (Dione vanillae, formerly Agraulis vanillae), found from Argentina to the southern United States with seasonal migrations reaching as far north as New Jersey and San Francisco, and Dione dodona, a recently described species restricted to xeric western slopes of the Andes in Peru and northern Chile. Members are characterized by bright orange and black coloration, association with Passifloraceae host plants, and chemical defense mechanisms.
Agraulis incarnata
Gulf Fritillary
Agraulis incarnata, commonly known as the Gulf Fritillary, is a brush-footed butterfly in the family Nymphalidae. The species is widely distributed across the southern United States, Mexico, Central America, and South America. Adults are characterized by bright orange upper wings with black markings and three white spots on the forewing. The caterpillars feed exclusively on passionflower vines (Passiflora spp.), sequestering cyanogenic glycosides from their host plants for chemical defense. The species is a sporadic migrant in northern parts of its range, occasionally establishing temporary colonies before winter mortality.
Alydidae
broad-headed bugs, broad headed bugs
Alydidae, commonly known as broad-headed bugs, is a family of true bugs in the order Hemiptera containing at least 60 genera and approximately 300 species worldwide. Members are characterized by their notably broad heads, often similar in length and width to the pronotum and scutellum, and elongated, curved terminal antennal segments. The family is closely related to Coreidae (leaf-footed bugs) and shares many morphological features, though Alydidae generally lack the flattened hind tibiae typical of many coreids. Most species are tropical or subtropical in distribution, with relatively few species occurring in temperate regions. Several species are economically significant agricultural pests, particularly in Asia where they damage rice and legume crops.
Amphibolips nubilipennis
translucent oak gall wasp
Amphibolips nubilipennis is a gall wasp in the family Cynipidae that induces distinctive succulent galls on oak trees. The species exhibits a complex life cycle with alternating sexual and asexual generations, each producing different gall types. The translucent oak gall formed by the sexual generation accumulates exceptionally high concentrations of malic acid, creating extremely acidic tissue conditions. This species has been documented across eastern North America and serves as a model organism for studying gall chemistry and plant-insect interactions.
Amphizoa
troutstream beetles
Amphizoa is a monogeneric genus of aquatic beetles, the sole representative of the family Amphizoidae. These beetles are commonly called troutstream beetles due to their association with cold, flowing mountain waters. The genus contains five known species, with three distributed in western North America and two in the eastern Palearctic region (China and North Korea). Adults and larvae are predatory, feeding primarily on stonefly larvae. When disturbed, adults release a yellowish, cantaloupe-scented fluid from the anus as a chemical defense.
Anisomorpha
two-striped walkingsticks, twostriped walkingsticks
Anisomorpha is a genus of large wingless walking stick insects (Phasmida) known for their potent chemical defense. Adults possess paired metathoracic glands that discharge an irritating secretion capable of causing intense burning pain and temporary blindness in predators, including humans. Females are substantially larger than males, with some individuals reaching nearly four inches in length. The genus contains four accepted species distributed across the southeastern United States, Central America, and northern South America.
Anisomorpha buprestoides
Southern Two-striped Walkingstick, Devil Rider, Musk Mare, Twostriped Walkingstick
Anisomorpha buprestoides is among the largest insects in the continental United States, with females reaching nearly 100 mm. This phasmid exhibits extreme sexual size dimorphism, with females substantially larger than males. The species is notable for its potent chemical defense spray containing anisomorphal and related compounds, which can cause severe eye irritation in humans. Three regionally distinct color morphs occur: brown, white, and orange forms, with the latter two restricted to specific areas of Florida.
Anisomorpha ferruginea
Northern Two-striped Walkingstick, Dark Walkingstick, Prairie Alligator
A large, sexually dimorphic walkingstick native to North America, recognized by two longitudinal pale stripes running the length of its dark brown to black body. Females are substantially larger than males. The species possesses chemical defense glands behind the head that can spray a noxious terpene dialdehyde mist when threatened. Active primarily in autumn when mating pairs are most frequently observed.
Apaturinae
emperors
Apaturinae is a subfamily of brush-footed butterflies (Nymphalidae) comprising approximately 20 genera and roughly 100 species commonly called 'emperors.' Members are distinguished by a green proboscis, strikingly colored upperwings, and cryptic underwings. The subfamily exhibits a disjunct global distribution, with most genera occurring in South and East Asia and Africa, while the genera Doxocopa and Asterocampa are primarily Neotropical and Nearctic. Larvae of at least some species possess a unique defensive mechanism: oral emission of volatile halitosis (alcohols and aldehydes/ketones with 4–5 carbon chains) when disturbed by predators.
Apheloria
cherry millipedes, flat-backed millipedes
Apheloria is a genus of large, chemically defended millipedes in the family Xystodesmidae, distributed across eastern North America. These millipedes are notable for producing hydrogen cyanide and benzaldehyde as defensive secretions, which imparts a characteristic cherry or almond odor. The genus participates in Müllerian mimicry rings in the Appalachian Mountains, with species displaying highly variable aposematic coloration involving black backgrounds with contrasting yellow, orange, red, or white markings. Species-level identification requires examination of male gonopod morphology due to extensive color polymorphism and convergent color patterns among co-occurring species.
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.
Apheloriini
cherry millipedes
Apheloriini is a tribe of large, colorful flat-backed millipedes endemic to the temperate forests of eastern North America. All species produce hydrogen cyanide as a chemical defense, which generates a characteristic cherry or almond odor from benzaldehyde byproducts. Members display bright aposematic coloration warning predators of their toxicity. The tribe includes seven genera, with greatest diversity concentrated in the southern Appalachian Mountains. Species in this tribe participate in Müllerian mimicry rings, resulting in extreme intraspecific variation in color patterns.
Aphis nerii
oleander aphid, milkweed aphid, sweet pepper aphid, nerium aphid
Aphis nerii is a cosmopolitan aphid species in the family Aphididae, primarily associated with plants in the dogbane family (Apocynaceae), especially milkweeds (Asclepias) and oleander (Nerium oleander). The species exhibits complex reproductive strategies including parthenogenesis and viviparity, with winged and wingless female morphs. It is a significant pest of ornamental plants and a known vector of multiple plant viruses. The species has been introduced widely beyond its native range and is now found in tropical, Mediterranean, and temperate regions globally.
Apiomerus flaviventris
Yellow-bellied Bee Assassin, bee assassin bug
Apiomerus flaviventris is a predatory assassin bug in the family Reduviidae, commonly known as the yellow-bellied bee assassin. This species is notable for its specialized feeding habits targeting bees and its remarkable use of plant-derived chemical defenses. Females collect resin from brittlebush (Encelia farinosa) and apply it to their eggs as a protective barrier against predation, particularly by ants. The species inhabits arid and semiarid regions of southwestern North America.
Arctia plantaginis
wood tiger, wood tiger moth
Arctia plantaginis, commonly known as the wood tiger moth, is a Holarctic moth species in the family Erebidae. Males exhibit striking color polymorphism with yellow or white hindwing morphs, both featuring black banding patterns that function as aposematic warning signals. The species has been extensively studied as a model organism for understanding the evolutionary trade-offs between predator avoidance, sexual selection, immune function, and thermoregulation. Larvae show predator-induced plasticity in warning signal expression, developing more melanized coloration when exposed to predation risk.
Arctiinae
Tiger Moths and Allies, Tiger Moths, Woolly Bear Moths, Footmen, Lichen Moths, Wasp Moths
Arctiinae is a large and diverse subfamily of moths within the family Erebidae, comprising approximately 11,000 species worldwide. The subfamily includes tiger moths, footmen, lichen moths, and wasp moths. Many species are characterized by aposematic coloration, chemical defenses, and the production of ultrasonic sounds for defense and communication. The group was formerly classified as the family Arctiidae but was reclassified as a subfamily of Erebidae based on phylogenetic studies.
Battus
Pipevine Swallowtails and Allies
Battus is a New World genus of swallowtail butterflies in the family Papilionidae. The genus comprises approximately 9 species distributed across the Americas, with the most well-known North American representatives being Battus philenor (pipevine swallowtail) and Battus polydamas (Polydamas swallowtail). All members share a specialized ecological relationship with pipevine plants (Aristolochia), which serve as their exclusive larval host plants. The genus is notable for its aposematic coloration and chemical defense system derived from sequestered toxins.
Battus philenor
pipevine swallowtail, blue swallowtail
Battus philenor, commonly known as the pipevine swallowtail or blue swallowtail, is a North American swallowtail butterfly distinguished by its iridescent blue hindwings and aposematic black coloration. The species is chemically defended throughout all life stages through sequestration of aristolochic acids from its obligate host plants in the genus Aristolochia. Females exhibit sophisticated host discrimination behavior, selecting plants based on leaf quality and bud characteristics. The butterfly serves as a model for Batesian mimicry by several palatable butterfly species. Populations in central California have shown resilience to drought conditions, contrasting with declines in montane butterfly faunas.
Battus philenor philenor
Pipevine Swallowtail, Blue Swallowtail
Battus philenor philenor is a subspecies of the pipevine swallowtail butterfly found in North America. Adults display iridescent blue hindwings against a black background, serving as aposematic warning coloration derived from sequestered aristolochic acids from their host plants. The subspecies is univoltine to bivoltine with flight periods from late winter through autumn, peaking before July. Populations have shown resilience to drought conditions in California's Central Valley, in contrast to montane butterfly declines.
Battus polydamas
Polydamas Swallowtail, Gold Rim Swallowtail, Tailless Swallowtail
Battus polydamas is a tailless swallowtail butterfly distinguished by black wings with yellow submarginal spots and red hindwing lunules. First described by Linnaeus in 1758, it occurs throughout the Neotropics and southern United States. Larvae are obligate specialists on Aristolochia (pipevine) plants, sequestering toxic aristolochic acids for chemical defense against predators.
Battus polydamas lucayus
Florida Polydamas Swallowtail, Polydamas Swallowtail, Gold Rim, Tailless Swallowtail
A tailless swallowtail butterfly distinguished by gold-rimmed black wings with red spots. Larvae feed exclusively on pipevine plants (Aristolochia) and sequester toxic aristolochic acids for chemical defense, rendering both caterpillars and adults unpalatable to vertebrate predators. Adults exhibit slow, weak flight and are active pollinators.
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.
Brachinus
bombardier beetles
Brachinus is a genus of ground beetles commonly known as bombardier beetles, native to the Nearctic, Palearctic, Near East, and North Africa. The genus is renowned for its explosive defensive chemistry, wherein beetles discharge a hot, noxious spray from the abdomen when disturbed. Species within Brachinus exhibit diverse ecological strategies: wetland-associated species are pupal ectoparasitoids of water beetles (Dytiscidae, Gyrinidae, Hydrophilidae), while dryland species such as B. explodens and B. crepitans parasitize ground beetle pupae of the genus Amara (Carabidae). The genus has been extensively studied for its chemical ecology, parasitoid life history, and habitat associations across agricultural and natural landscapes.
Brachinus aabaaba
Brachinus aabaaba is a species of bombardier beetle in the family Carabidae, first described by Terry Erwin in 1970. It belongs to the genus Brachinus, which is renowned for its chemical defense mechanism that produces a hot, noxious spray from the abdomen when disturbed. The species name 'aabaaba' is unusual and appears to be a non-standard formation, possibly reflecting a descriptive or arbitrary designation by the author. Records indicate this species occurs in Mexico and the southwestern United States.
Brachinus adustipennis
Brachinus adustipennis is a species of bombardier beetle in the family Carabidae, first described by Terry Erwin in 1969. It belongs to the genus Brachinus, which is renowned for its remarkable chemical defense mechanism—producing a hot, noxious spray from the abdomen when disturbed. The species occurs across a broad geographic range spanning the Caribbean, Central America, and North America, with confirmed records from Cuba, Mexico, Panama, and the United States.
Brachinus alexiguus
Brachinus alexiguus is a species of bombardier beetle in the family Carabidae, described by Erwin in 1970. As a member of the genus Brachinus, it possesses the characteristic defensive chemical spray mechanism for which these beetles are renowned. The species is known from North America, with confirmed records from the United States.
Brachinus alternans
Brachinus alternans is a species of bombardier beetle in the family Carabidae, characterized by its chemical defense mechanism. The species occurs in Central America and North America, including the United States. Like other members of the genus Brachinus, it possesses the ability to discharge a hot, noxious chemical spray from the abdomen as a defense against predators. The specific epithet 'alternans' refers to some alternating pattern in the original description, though the precise nature of this pattern is not detailed in available sources.
Brachinus costipennis
Brachinus costipennis is a species of bombardier beetle in the ground beetle family Carabidae, first described by Motschulsky in 1859. As a member of the genus Brachinus, it possesses the characteristic chemical defense system that defines this group: the ability to spray a hot, noxious mixture of benzoquinones from the abdomen when threatened. The species occurs in Central America and North America, with records from Guatemala, Mexico, and the United States.
Brachinus cyanipennis
Cyan-winged Bombardier Beetle
Brachinus cyanipennis is a bombardier beetle species in the family Carabidae, characterized by explosive defensive chemistry typical of the genus. Based on molecular phylogenetic analysis using COI, CAD, and 28S gene regions, this species was moved from Erwin's fumans species group to the newly erected cyanipennis species group within the subgenus Neobrachinus. The species is found in North America.
Brachinus cyanochroaticus
bombardier beetle
Brachinus cyanochroaticus is a species of bombardier beetle in the ground beetle family Carabidae. It is native to North America, with confirmed records from the United States and Canada. Like other members of the genus Brachinus, it possesses the distinctive defensive chemical reaction that gives bombardier beetles their common name. The species was described by Terry Erwin in 1969.
Brachinus favicollis
Brachinus favicollis is a species of bombardier beetle in the family Carabidae, described by Terry Erwin in 1965. Like other members of the genus Brachinus, this species possesses the remarkable defensive ability to eject a hot, noxious chemical spray from the tip of its abdomen when disturbed. The species occurs in the southwestern United States and Mexico.
Brachinus fulminatus
Brachinus fulminatus is a species of ground beetle in the family Carabidae, described by Erwin in 1969. The species is known from North America, with distribution records from the United States. Like other members of the genus Brachinus, it is expected to possess chemical defense capabilities, though specific details for this species remain undocumented.
Brachinus fumans
American bombardier beetle
Brachinus fumans, commonly known as the American bombardier beetle, is a ground beetle in the family Carabidae and subfamily Brachininae. This species belongs to the subgenus Neobrachinus and was originally placed in Erwin's fumans species group based on morphological characters, though molecular phylogenetic studies have redefined this group. The species is endemic to the Nearctic region and is found across North America. Like other bombardier beetles, it possesses remarkable explosive defensive chemistry.
Brachinus hirsutus
Brachinus hirsutus is a species of bombardier beetle in the family Carabidae, characterized by its ability to produce defensive chemical sprays. It is found in Central America and North America, with records from Mexico and the United States. Like other members of the genus Brachinus, it possesses specialized defensive glands that can discharge hot, noxious chemicals when threatened.
Brachinus janthinipennis
Brachinus janthinipennis is a species of bombardier beetle in the family Carabidae, native to North America. Like other members of the genus Brachinus, it possesses the remarkable defensive ability to discharge a hot, noxious chemical spray from its abdomen when threatened. The species occurs in Canada and the United States, though specific details about its biology and ecology remain poorly documented in the scientific literature.
Brachinus medius
Medial Bombardier Beetle
Brachinus medius is a species of bombardier beetle in the family Carabidae. It is one of approximately 40 species in the genus Brachinus found in North America. Like other members of its genus, it possesses the remarkable defensive ability to discharge a hot, noxious chemical spray from the tip of its abdomen when threatened. The species occurs across much of North America including the United States, Canada, and Mexico.
Brachinus pallidus
Brachinus pallidus is a bombardier beetle in the family Carabidae, first described by Erwin in 1965. Like other members of the genus Brachinus, it possesses the remarkable chemical defense system for which bombardier beetles are famous: paired glands that combine hydroquinones and hydrogen peroxide to produce a hot, noxious spray of benzoquinones when threatened. The species is known from California and represents part of the diverse North American fauna of this chemically defended ground beetle genus.
Brachinus phaeocerus
Brachinus phaeocerus is a species of ground beetle in the family Carabidae, first described by Chaudoir in 1868. It belongs to the bombardier beetle genus Brachinus, notable for its chemical defense mechanism. The species occurs in Central America and North America, including Mexico and the United States. Like other members of its genus, it possesses the characteristic ability to produce and eject defensive chemicals when threatened.
Brachinus puberulus
Brachinus puberulus is a species of bombardier beetle in the family Carabidae, described by Chaudoir in 1868. It belongs to the genus Brachinus, renowned for its chemical defense mechanism that produces a hot, noxious spray from the abdomen when disturbed. The species is recorded from the United States and Middle America, though specific details about its biology and ecology remain sparse in the available literature.
Brachinus quadripennis
Square-winged Bombardier Beetle
Brachinus quadripennis is a species of ground beetle in the family Carabidae, commonly known as the Square-winged Bombardier Beetle. It belongs to the bombardier beetle genus Brachinus, which is renowned for its chemical defense mechanism. The species is found in Central America and North America, with records from Canada, the United States, and Middle America.
Brachinus texanus
Brachinus texanus is a species of bombardier beetle in the family Carabidae. Like other members of its genus, it possesses a remarkable defensive chemical mechanism, spraying a hot, corrosive liquid from its abdomen when disturbed. The species occurs in North America, with records from the United States and Canada.
Brachinus vulcanoides
Brachinus vulcanoides is a species of bombardier beetle in the ground beetle family Carabidae, first described by Erwin in 1969. As a member of the genus Brachinus, it possesses the characteristic defensive chemical spray mechanism that defines this group. The species is known from North America, specifically recorded from the United States, though detailed natural history information remains limited in the available literature.
Brachycybe petasata
Brachycybe petasata is a small millipede in the order Platydesmida, endemic to the southern Appalachian Mountains of the southeastern United States. It inhabits moist forest floor habitats, particularly leaf litter and decaying wood in beech, birch, maple, and hemlock forests. The species is distinguished by its production of four unique monoterpene alkaloids as chemical defenses: gosodesmine, hydrogosodesmine, homogosodesmine, and hydrohomogosodesmine. As a member of the subterclass Colobognatha, it represents one of the few millipede lineages known to synthesize terpenoid alkaloids.
Brevicoryne brassicae
cabbage aphid, cabbage aphis, mealy cabbage aphid
Brevicoryne brassicae, commonly known as the cabbage aphid, is a destructive agricultural pest native to Europe that has spread worldwide. The species feeds exclusively on plants in the family Brassicaceae, including cabbage, broccoli, Brussels sprouts, cauliflower, and other cultivated brassicas. Large colonies form on the undersides of young leaves and flower heads, causing significant yield losses through direct feeding damage and virus transmission. The aphid possesses a unique chemical defense mechanism, producing myrosinase enzyme and sequestering glucosinolates from host plants to release toxic mustard oil compounds when attacked.
Callosamia promethea
Promethea Silkmoth, Spicebush Silkmoth
Callosamia promethea is a North American silk moth in the family Saturniidae, notable for being the only member of its family with sexually dimorphic activity patterns: males are diurnal while females are nocturnal. Adults do not feed. Larvae feed on a broad range of host plants across multiple families, including Rosaceae, Oleaceae, and Lauraceae. The species produces silk for cocoon construction and exhibits distinctive defensive behaviors including thanatosis and chemical secretion.
Calosoma marginale
rimmed caterpillar hunter, Wrinkle-winged Calosoma
A large ground beetle in the genus Calosoma, commonly known as the rimmed caterpillar hunter. Adults are crepuscular and active predators that hunt caterpillars and scarabaeid beetles. The species occurs across a broad geographic range from Central America through the southern and central United States. Adults overwinter in the ground.