Sexual-dimorphism
Guides
Atlanticus testaceus
protean shieldback, short-legged shield-bearer
Atlanticus testaceus, commonly called the protean shieldback or short-legged shield-bearer, is a shield-backed katydid native to eastern North America. The species exhibits pronounced sexual dimorphism in diet: adult females are primarily carnivorous while adult males consume mostly dried leaves and sand. Both sexes are known to engage in cannibalism. Activity is concentrated in the evening hours, with males stridulating intensively from elevated vegetation while females search for mates and prey.
Aulocara femoratum
Whitecrossed Grasshopper, White Cross Grasshopper, White-crossed Grasshopper
Aulocara femoratum, commonly known as the whitecrossed grasshopper, is a medium-sized slant-faced grasshopper inhabiting western North American grasslands. It is a generalist grass feeder that occasionally reaches pest status in mixedgrass prairie habitats, though it is typically subdominant to its congener Aulocara elliotti. The species exhibits sexual dimorphism in both size and feeding behavior, with males being smaller and more mobile while females are larger and more sedentary. It completes one generation annually, overwintering as eggs.
Auridius safra
Auridius safra is a leafhopper species in the family Cicadellidae, described from the western United States in 1999. The species is characterized by yellow coloration and pronounced sexual dimorphism in both color and wing form. It inhabits shortgrass prairie ecosystems and exhibits wing polymorphism with both fully-winged (macropterous) and short-winged (brachypterous) individuals.
Automeris io
Io moth, peacock moth
Automeris io is a colorful North American saturniid moth with sexual dimorphism in adult coloration: males are bright yellow, females reddish-brown to purple. Both sexes possess distinctive eyespots on the hindwings used in anti-predator displays. The caterpillars are gregarious, bright green with red and white lateral stripes, and possess venomous urticating spines that cause painful stings. Adults are nocturnal, lack functional mouthparts, and live 1–2 weeks. Populations have declined in parts of their range, particularly in New England, due to habitat loss and parasitism by introduced biological control agents.
Baeus
micro-flea wasp
Baeus is a genus of minute parasitoid wasps in the family Scelionidae, remarkable for extreme sexual dimorphism. Females are wingless, highly compact, and flea-like in appearance with reduced or fused body segments, while males possess wings and a more typical scelionid morphology. All species are endoparasitoids of spider eggs, developing inside the oothecae (egg sacs) of diverse spider families. The genus has a cosmopolitan distribution across all continents except Antarctica, with greatest species diversity documented along the eastern seaboard of Australia.
Bagheera prosper
Bagheera prosper is a species of jumping spider in the family Salticidae, first described by Peckham & Peckham in 1901. The species exhibits notable sexual dimorphism in cheliceral structure: males possess long, parallel chelicerae with a large spiral embolus on the prolateral side of the palpal bulb, while females have regular-sized chelicerae and epigynal openings located in spiral atria. It is considered fairly common but difficult to detect due to its cryptic coloration.
Bassaniana versicolor
Multicolored Bark Crab Spider
Bassaniana versicolor is a crab spider in the family Thomisidae, native to North America. Females reach 6.75 mm in length, while males are smaller at 3.8–4.5 mm. The species exhibits color variation with a brown body marked by white spots. It is commonly known as the Multicolored Bark Crab Spider.
Belidae
Primitive Weevils, Belids, Cycad Weevils (restricted usage)
Belidae is an ancient family of weevils distinguished from true weevils (Curculionidae) by straight rather than elbowed antennae. The family exhibits a relictual Gondwanan distribution, with extant species found primarily in the Australia–New Guinea–New Zealand region, South and Central America, Southeast Asia, Pacific islands, and scattered African localities. Belidae comprises two living subfamilies: Belinae and Oxycoryninae. The family has undergone significant host-plant shifts from ancestral conifer associations to diverse angiosperm lineages, including cycads, palms, and parasitic flowering plants.
Belostoma lutarium
giant water bug
Belostoma lutarium is a species of giant water bug in the family Belostomatidae, native to North America. This aquatic insect is notable for its distinctive paternal care behavior, in which males carry egg clutches on their backs until hatching—a rare form of male parental investment in insects. The species exhibits sexual dimorphism with females being the larger sex, and studies suggest males may be the choosier sex in mate selection. As a predator, it feeds on aquatic invertebrates, small fish, and amphibian larvae including tadpoles.
Besma quercivoraria
Oak Besma, Oak Besma Moth
Besma quercivoraria, the oak besma, is a North American geometrid moth with two generations per year. Adults are sexually dimorphic and active from spring through summer, with timing varying by latitude. The species is notable for its broad host plant range among deciduous trees and conifers.
Bibio articulatus
red-legged march fly
Bibio articulatus is a species of march fly in the family Bibionidae, commonly known as the red-legged march fly. It is distinguished by its dark exoskeleton ranging from black to deep red and its conspicuous red or orange legs. The species exhibits pronounced sexual dimorphism, particularly in eye size and body proportions. It is most active during spring months and is found primarily in the eastern United States.
Bibio slossonae
March fly
Bibio slossonae is a species of March fly in the family Bibionidae, described by Cockerell in 1909. Like other members of its genus, it exhibits pronounced sexual dimorphism in head structure. The species has been documented as a pollinator of witch-hazel (Hamamelis virginiana), representing a notable plant-insect interaction.
Bibio superfluus
Garden Maggot
Bibio superfluus, commonly known as the Garden Maggot, is a species of march fly in the family Bibionidae. Adults are active in spring, with males forming conspicuous swarms that attract females for mating. The species exhibits strong sexual dimorphism in head structure. Larvae develop in soil where they feed on decaying organic matter and plant roots.
Bibio xanthopus
yellow-footed March fly
Bibio xanthopus, commonly known as the yellow-footed March fly, is a species of March fly in the family Bibionidae first described by Wiedemann in 1828. It is one of the most common species of Bibio in North America. The species exhibits considerable size variation and displays distinct sexual dimorphism in head morphology and wing coloration.
Blastophaga psenes
Common Fig Wasp
Blastophaga psenes is a minute chalcidoid wasp, approximately 2 mm in length, and the obligate pollinator of Ficus carica (common fig) and Ficus palmata. Females are winged, black, and shiny; males are smaller, wingless, and do not disperse from the fig. The species exhibits extreme sexual dimorphism and a highly specialized mutualistic relationship with its host figs. Adults live only a few days to weeks, breeding exclusively within fig syconia without constructing nests or colonies. The species is native to the Palaearctic region and has been introduced globally to support commercial fig cultivation.
Blattinae
Blattinae is a subfamily of cockroaches in the family Blattidae, established by Latreille in 1810. It includes several of the most common household cockroach species, notably Periplaneta americana (American cockroach) and Blatta orientalis (Oriental cockroach). The subfamily is characterized by male genitalia with diagnostic sclerites, and includes genera with diverse morphologies ranging from fully winged macropterous males to reduced-winged females in sexually dimorphic species.
Boloria alberta
Alberta fritillary
Boloria alberta is a small alpine fritillary butterfly endemic to the North American Rocky Mountains. Adults fly from July to early August in high-elevation habitats. The species exhibits sexual dimorphism in coloration, with males appearing dull orange and females pale orange to gray-brown. Larvae are specialized feeders on mountain avens (Dryas octopetala).
Boopedon
boopies, ebony grasshopper (B. nubilum), yellow-belly boopie (B. flaviventris), prairie boopie (B. gracile), short-winged boopie (B. auriventris)
Boopedon is a genus of grasshoppers in the family Acrididae, commonly known as boopies. The genus contains at least eight described species distributed across western North American grasslands. Species in this genus are notable for pronounced sexual dimorphism, with males typically winged and darkly colored while females are often larger, flightless, and paler. Several species, particularly B. nubilum (the ebony grasshopper), are significant rangeland pests capable of reaching outbreak densities.
Boopedon nubilum
ebony grasshopper, black-males grasshopper, plains boopie
Boopedon nubilum is a large slant-faced grasshopper inhabiting western North American grasslands. Males are strikingly black with functional wings, while females are large, pale brown, and typically flightless. The species is a specialized grass feeder with documented food preferences that vary geographically. At high densities, it becomes a significant pest of rangeland forage, particularly in the southern mixedgrass and desert prairies of Arizona, New Mexico, and western Texas.
Brachiacantha bollii
Boll's lady beetle, Confluent-spotted Spurleg
Brachiacantha bollii, commonly known as Boll's lady beetle, is a small species of lady beetle in the family Coccinellidae. Adults measure approximately 2.40–3 mm in length. The species exhibits sexual dimorphism in pronotal coloration: males have a black pronotum with the anterior one-third yellow, while females have a black pronotum with a yellow anterolateral angle. The elytra display five large round spots. It has been recorded from Louisiana and Texas in North America.
Brachiacantha dentipes
Brachiacantha dentipes is a small lady beetle (family Coccinellidae) native to North America. Adults measure 4.75–6.30 mm in length. The species exhibits sexual dimorphism in pronotum coloration: males have a black pronotum with yellow or orange anterior margin and lateral areas, while females have a similar pattern but with a black anterior margin. The elytra are black with an orange or yellow apical spot and a median band. The subspecies B. dentipes americana Leng, 1911 has been synonymized with the nominate form.
Brachiacantha felina
Orange-spotted Lady Beetle
Brachiacantha felina is a small lady beetle in the family Coccinellidae, native to eastern and central North America. Adults measure 2.2–3 mm and exhibit distinct sexual dimorphism in pronotum coloration. The species is known from scattered records across its range, with relatively few observations documented.
Brachiacantha indubitabilis
Small-spotted Spurleg
Brachiacantha indubitabilis is a minute lady beetle (Coccinellidae) distinguished by strong sexual dimorphism in coloration. Males display a yellow head and black pronotum with yellow anterior margin, while females have a yellowish-brown head and laterally yellow pronotum. Both sexes share black elytra marked with three yellow spots. The species is recorded from the northeastern and midwestern United States.
Brachiacantha quadripunctata
Four-spotted Spurleg
Brachiacantha quadripunctata is a small lady beetle in the family Coccinellidae, native to North America. Adults measure 2.5–4.0 mm and exhibit distinct sexual dimorphism in head coloration and elytral spot patterns. The species comprises two recognized subspecies with partially overlapping but distinct geographic ranges in the eastern and southeastern United States.
Brachiacantha stephani
Stephan's lady beetle
Brachiacantha stephani, known as Stephan's lady beetle, is a small lady beetle species in the family Coccinellidae. Adults exhibit distinctive coloration with black bodies marked by yellow and reddish-orange patterns on the pronotum and elytra. The species is known from a limited geographic range in North America, specifically recorded from Arizona. It is named in honor of Karl Stephan, collector of part of the type series.
Brachycistidinae
Brachycistidinae is a subfamily of flower wasps (Tiphiidae) containing 10 genera and 85 species endemic to the Nearctic region. These wasps exhibit extreme sexual dimorphism: females are wingless and ant-like, living primarily underground, while males are winged and nocturnal. The subfamily has historically suffered from "dual taxonomy," where sexes were described as separate species due to their dissimilar appearance. Taxonomic resolution remains challenging due to structural similarities among species and lack of distinctive coloration.
Brachypanorpa
short-nosed scorpionfly
Brachypanorpa is a genus of scorpionflies in the family Panorpodidae, containing five described species distributed in a disjunct pattern across eastern North America and the Pacific Northwest. The genus exhibits pronounced sexual dimorphism in mouthpart morphology: females possess elongated mouthparts adapted for feeding on subcortical fluids, while males have shorter mouthparts. Larvae develop within decaying wood, functioning as decomposers in forest ecosystems.
Brachypsectra
Texas beetle
Brachypsectra is a genus of beetles in the family Brachypsectridae, one of two extant genera in this small elateroid family. Adults are small, light brown beetles with distinctive pectinate antennae in males. The larvae are flattened, ovate predators with branched lateral lobes on thoracic and abdominal segments, historically known as an 'entomological enigma' before their adult form was discovered. The genus occurs in southwestern North America, with larvae found under bark, in leaf litter, and rock crevices.
Brachypsectridae
Texas beetles
Brachypsectridae is a small family of beetles in the superfamily Elateroidea, commonly known as Texas beetles. The family contains two extant genera—Brachypsectra (cosmopolitan in arid regions) and Asiopsectra (Central Asia and Middle East)—plus several fossil genera from Cretaceous amber. Adults are small, soft-bodied beetles lacking the functional prothoracic clicking mechanism typical of related elateroids. Larvae are highly distinctive ambush predators with flattened bodies and feathery lateral lobes.
Brachypylina
Brachypylina is a diverse infraorder of oribatid mites (beetle mites) comprising the majority of oribatid species. These mites are characterized by heavily armored, beetle-like bodies with a distinct separation between the notogastral shield and other body regions. They occupy a wide range of terrestrial habitats and play significant roles in decomposition and nutrient cycling.
Brentidae
straight-snouted weevils, primitive weevils
Brentidae is a cosmopolitan family of weevils distinguished by their straight (non-elbowed) antennae and elongated, often flattened bodies. The family has undergone significant taxonomic expansion, now encompassing approximately 4,000 species across six subfamilies including groups formerly classified in Curculionidae (Apioninae, Cyladinae, Nanophyinae) and the previously separate family Ithycerinae. Members are primarily xylophagous, with larvae feeding on fungi in dead wood. The family exhibits its greatest diversity in tropical regions but extends into temperate zones worldwide.
Brentinae
straight-snouted weevils, primitive weevils
Brentinae is a subfamily of primitive weevils in the family Brentidae, commonly called straight-snouted weevils. Members are distinguished from true weevils (Curculionidae) by their straight, elongated rostrum rather than a geniculate (elbowed) snout. The subfamily contains at least 90 genera and 520 described species, with extreme sexual dimorphism in rostrum and mandible structure observed in some species. The type genus Brentus was used by Gustaf Johan Billberg to establish both the subfamily and family in 1820.
Brentus
Brentus is the type genus of primitive weevils in the family Brentidae and tribe Brentini. Species are distributed in the Americas, with most diversity occurring in tropical regions. The genus exhibits extreme sexual dimorphism in rostrum and mandible morphology, with females possessing elongated, slender rostrums for wood-boring oviposition and males having short, robust mandibles used in territorial combat. These beetles develop as larvae in the wood of living or wounded trees.
Cacoecimorpha pronubana
Carnation Tortrix, Carnation Leaf-roller
Cacoecimorpha pronubana is a highly polyphagous tortricid moth of Mediterranean origin, now widespread across Europe, North Africa, and introduced to North America and South Africa. The sole species in its genus, it is a significant pest of ornamental plants and horticultural crops. Larvae feed on foliage, flowers, and fruits, rolling leaves with silken webbing to create concealed feeding shelters. The species exhibits complex transgenerational responses to host plant changes, with parental diet affecting offspring development and reproduction.
Caenocholax
Caenocholax is a genus of twisted-winged insects (Strepsiptera) in the family Myrmecolacidae, comprising approximately nine described species. Members are endoparasitoids of ants, with documented associations including Solenopsis invicta and Camponotus planatus. The genus exhibits the extreme sexual dimorphism characteristic of Strepsiptera: males are free-living with reduced forewings and large fan-shaped hindwings, while females remain endoparasitic and neotenic within the host.
Caenocholax fenyesi
Caenocholax fenyesi is a strepsipteran parasitoid in the family Myrmecolacidae, notable for extreme sexual dimorphism and heterotrophic heteronomy—males and females occupy different hosts throughout their life cycles. Females are endoparasites of Orthoptera, while males parasitize ant larvae and pupae, primarily Solenopsis invicta (red imported fire ant) in the United States and related native fire ants in Mexico, Central America, and parts of South America. The species has a sporadic distribution across the southern United States, Central America, and South America, with three recognized cryptic subspecies that are morphologically similar but genetically distinct. Adult males are free-living with a lifespan of only hours to a few days, severely constraining dispersal and contributing to genetic bottlenecking effects.
Callicorixa vulnerata
water boatman
Callicorixa vulnerata is a species of water boatman (family Corixidae) found in North America. The species exhibits sexual size dimorphism, with documented research focusing on tarsal asymmetry and trait size variation in relation to fitness. Mid-leg tarsi are used to cling to bottom substrate during underwater feeding. The species was described by Uhler in 1861 and is currently accepted under the genus Callicorixa.
Callidiellum villosulum
A small longhorn beetle (Cerambycidae: Cerambycinae: Callidiini) characterized by sexual dimorphism in mouthpart morphology. Adult females possess larger labial and maxillary palps with more developed sensilla basiconica IV, sensilla campaniformia, and sensilla chaetica II, structures associated with oviposition site selection. Males exhibit more developed sensilla basiconica I, potentially involved in mate recognition. The species has been subject to detailed scanning electron microscopy studies of its chemosensory and mechanosensory mouthpart structures.
Callinectes sapidus
blue crab, Atlantic blue crab, Maryland blue crab
Callinectes sapidus is a large portunid crab native to the western Atlantic Ocean and Gulf of Mexico, with established invasive populations in Europe, Asia, and elsewhere via ballast water transport. The species exhibits pronounced sexual dimorphism in abdominal shape and claw coloration. It supports major commercial fisheries, particularly in the Chesapeake Bay and Gulf of Mexico, though populations have declined in some areas due to overfishing and environmental degradation. As an invasive species, it damages fishing gear and competes with native species in introduced ranges.
Calliopsis pugionis
Pugnosed Miner Bee
Calliopsis pugionis is a solitary ground-nesting bee in the family Andrenidae, described by Cockerell in 1925. It is found in North America, where it excavates burrows in sandy soil. The species exhibits sexual dimorphism with females larger than males, and has a female-biased investment sex ratio consistent with local mate competition theory. It serves as the host for the cleptoparasitic bee Holcopasites ruthae.
Calliopsis zebrata
Streaked Miner Bee
Calliopsis zebrata, commonly known as the streaked miner bee, is a ground-nesting solitary bee in the family Andrenidae. It is notable among Calliopsis species for having relatively large males. The species inhabits sandy soils in plains and prairie environments and has been documented visiting flowers of White Prairie Clover (Dalea candida). It is found in North America, with observations from Colorado and other regions.
Callophrys eryphon
Western Pine Elfin
Callophrys eryphon, the Western Pine Elfin, is a North American lycaenid butterfly with a transcontinental range spanning from British Columbia to Maine and south to southern California, Arizona, and New Mexico. Adults are sexually dimorphic: males are brown while females are orange-brown, both featuring bold patterned hindwings with dark bars and lighter chevron-shaped margins on the upper wing surfaces. The species is small, with body lengths of 19–32 mm and no tail on the hindwings.
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.
Callosobruchus maculatus
cowpea weevil, cowpea seed beetle, bean beetle
Callosobruchus maculatus is a seed beetle (family Chrysomelidae, subfamily Bruchinae) commonly known as the cowpea weevil or cowpea seed beetle, despite not being a true weevil. It is a major pest of stored legumes, particularly cowpea (Vigna unguiculata), causing seed losses of 60–100% in infested stores. The species has a cosmopolitan distribution across all continents except Antarctica, having spread globally through human trade of legumes. It exhibits notable sexual dimorphism, with females typically darker and larger than males. The species is widely used as a model organism in evolutionary biology, behavioral ecology, and developmental studies due to its rapid generation time, ease of laboratory rearing, and well-characterized life history.
Calopterygidae
broad-winged damselflies, demoiselles, jewelwings
Calopterygidae is a family of damselflies in the suborder Zygoptera, containing approximately 150 species. Members are relatively large for damselflies, with wingspans of 50–80 mm, and are characterized by broad wings with wide bases, metallic coloration, and a distinctive flight pattern described as jerky and fluttering. The family is distributed across all continents except Antarctica, primarily associated with running water habitats.
Calpini
fruit-piercing moths, vampire moths
Calpini is a tribe of fruit-piercing moths in the family Erebidae, formerly placed in Noctuidae. Adults possess a pointed, barbed proboscis adapted for piercing fruit skin to feed on juice. The genus Calyptra within this tribe includes species known as vampire moths, which can pierce mammal skin to drink blood. This blood-feeding behavior is facultative and restricted to males; females feed exclusively on fruit juice and nectar.
Caprella mutica
Japanese Skeleton Shrimp
Caprella mutica is a highly invasive caprellid amphipod native to the Sea of Japan. It has spread to temperate coastlines worldwide through maritime shipping and aquaculture, becoming established in the North Atlantic, North Pacific, New Zealand, and most recently South America. The species exhibits pronounced sexual dimorphism, with males reaching 50 mm and females averaging 15–20 mm. It is characterized by densely setose first and second pereonites in males and remarkable ecological plasticity, enabling dense populations on artificial structures.
Caprellidae
Skeleton Shrimp, Ghost Shrimp
Caprellidae is a family of marine amphipods known as skeleton shrimps, characterized by their slender, threadlike bodies that provide camouflage among seaweed, hydroids, and bryozoans. They exhibit extreme sexual dimorphism, with males typically much larger than females. The family contains 88 genera across three subfamilies and is distributed worldwide in marine environments from intertidal zones to deep sea depths. Some species have been documented as invasive, spreading through biofouling on aquaculture equipment.
Carmenta tildeni
Carmenta tildeni is a small clearwing moth in the family Sesiidae, described by Thomas D. Eichlin in 1995. It is native to the southwestern United States (Arizona and southern Texas) and Mexico. The species exhibits sexual dimorphism in size, with females notably smaller than males. As a member of the clearwing moth genus Carmenta, it likely possesses reduced wing scaling that creates a wasp-like appearance, though specific behavioral and ecological details remain poorly documented.
Carynota mera
Carynota mera is a species of treehopper in the family Membracidae, first described by Thomas Say in 1830 as Membracis mera. It is distinguished from other members of the tribe Telamonini by its rounded pronotum. The species exhibits sexual dimorphism in size, with females being larger than males. It is distributed across the eastern United States and eastern Canada.