Parthenogenesis
Guides
Podon
Podon is a genus of marine cladocerans in the family Podonidae, characterized by onychopod morphology. The genus includes at least four described species: P. intermedius, P. leuckarti, P. leuckartii, and P. schmackeri. Members are euryhaline and eurythermal, inhabiting estuarine and coastal marine waters. Populations exhibit strong seasonal dynamics, with spring and fall peaks and summer disappearance in temperate regions.
Polyphemus pediculus
Polyphemus pediculus is a predatory freshwater cladoceran crustacean in the family Polyphemidae. It is distributed throughout the Northern Hemisphere but exhibits significant genetic structuring, representing at least nine largely allopatric cryptic species rather than a truly cosmopolitan population. The species displays complex reproductive behavior involving both parthenogenetic and gamogenetic (sexual) phases, with pronounced seasonal and daily rhythms in swarming activity.
Polyxenus lagurus
Bristly Millipede
Polyxenus lagurus, commonly known as the bristly millipede, is a small millipede species distinguished by its detachable defensive bristles that entangle attacking ants and spiders. It exhibits a unique reproductive polymorphism, with some populations reproducing sexually and others parthenogenetically. This species undergoes hemianamorphosis, adding segments and legs through juvenile molts until reaching a fixed adult complement of 13 leg pairs and 10 tergites, after which molting continues without further segment addition. It is the most common polyxenid in Europe and the only representative of order Polyxenida in the British Isles.
Poratia
Poratia is a genus of minute polydesmidan millipedes in the family Pyrgodesmidae, characterized by obligate parthenogenetic reproduction via thelytoky. The genus includes Poratia salvator, a small species (3.5 mm length, 0.5 mm width, 19 body segments, brownish-yellow coloration) originally described from El Salvador and recorded from Brazil. Populations exhibit ecological plasticity, inhabiting both strictly terrestrial and periodically inundated environments. Reproduction is independent of males, with extremely skewed sex ratios (approximately 1 male:140 females) and flavobacteria-mediated parthenogenesis demonstrated at the genus level.
Pristiphora geniculata
mountain ash sawfly, rowan leaf sawfly, Ebereschen-Blattwespe
Pristiphora geniculata is a sawfly species in the family Tenthredinidae, native to the Palaearctic region and introduced to North America. It is a specialized herbivore of Sorbus species, particularly mountain ash (rowan). The species exhibits facultative parthenogenesis and shows pronounced sexual dimorphism in larval development, with females having five instars compared to four in males. In eastern Canada, it typically produces two generations annually, though only one in northern Quebec and at higher elevations in Europe. The species has been the target of successful classical biological control programs using the parasitoid wasp Olesicampe geniculatae.
Procambarus
crayfish, crawfish, crawdad
Procambarus is a genus of freshwater crayfish in the family Cambaridae, native to North and Central America. The genus contains approximately 160 species in 16 subgenera, making it one of the most species-rich crayfish genera. It includes both widespread surface-dwelling species and numerous troglobitic (cave-dwelling) species. The marbled crayfish (marmorkrebs), a parthenogenetic form, is also classified within this genus. Several species, particularly P. clarkii (red swamp crayfish), have been introduced globally and are recognized as invasive species with significant ecological and economic impacts.
Procambarus fallax
Slough Crayfish, Deceitful Crayfish
Procambarus fallax is a freshwater crayfish native to peninsular Florida and southern Georgia, USA, where it inhabits tributaries of the Satilla River. The species is notable as the sexual parental species of the parthenogenetic Marmorkrebs (marbled crayfish), which originated as a single lineage from P. fallax through apomictic parthenogenesis. While P. fallax reproduces sexually with separate males and females, its parthenogenetic derivative has achieved global distribution through the aquarium trade and exhibits high invasive potential due to single-female founding capability.
Protaphorura
Protaphorura is a genus of springtails (Collembola) in the family Onychiuridae, established by Absolon in 1901. The genus contains numerous species distributed across the Palearctic region, with particular diversity in southern Siberia and the Far East of Russia. Several species are obligate cave-dwellers (troglobionts), exhibiting specialized adaptations to subterranean environments. The genus is taxonomically well-studied, with identification keys available for over 85 Palearctic species based on morphological characters including pseudocellar formulae, postantennal organ structure, and chaetotaxy.
Protopulvinaria pyriformis
Pyriform Scale
Protopulvinaria pyriformis, commonly known as the pyriform scale, is a soft scale insect in the family Coccidae. It is a significant agricultural pest primarily associated with avocado, though it has been recorded on citrus and other hosts. The species exhibits parthenogenetic reproduction in most populations and possesses the unusual ability for a soft scale to move around as an adult female. It is known from multiple continents including Australia, Africa, Europe, and the Americas.
Psocodea
bark lice, book lice, parasitic lice, barklice, booklice
Psocodea is an order of insects comprising approximately 11,000 species across three extant suborders: Trogiomorpha, Troctomorpha, and Psocomorpha. The group includes free-living barklice and booklice, as well as the parasitic lice (formerly Phthiraptera). Molecular and morphological evidence demonstrates that parasitic lice evolved from within the barklice lineage, rendering the former order 'Psocoptera' paraphyletic. Members range from 1–10 mm in length and occupy diverse habitats from forest canopies to stored products.
Ptinella
Ptinella is a genus of minute featherwing beetles in the family Ptiliidae, characterized by extreme body miniaturization and reduced wing venation. The genus exhibits remarkable adaptive traits including wing polymorphism (presence of both winged and wingless morphs) and parthenogenesis in some species. These features appear to be evolutionary responses to the spatially and temporally heterogeneous subcortical habitat where members of this genus occur.
Purshivora media
Purshivora media is a species of aphid in the family Aphididae. It is a specialist feeder associated with plants in the genus Purshia, commonly known as bitterbrush or cliffrose. The species is native to western North America where its host plants occur in arid and semi-arid shrubland habitats. Like other aphids, it reproduces parthenogenetically during favorable conditions.
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surinamensis
Surinam cockroach, greenhouse cockroach
Pycnoscelus surinamensis is a burrowing cockroach endemic to the Indomalayan region that has become established in tropical and subtropical regions worldwide. Populations are almost exclusively female, reproducing parthenogenetically through multiple clonal strains. The species is a common plant pest that has been transported globally in soil of potted plants, establishing in greenhouses and other protected habitats. It completes its life cycle in approximately 135 days through four nymphal instars. The species serves as an intermediate host for the poultry parasite Oxyspirura mansoni and exhibits unique false ovoviviparous reproduction where females retain the ootheca internally for an extended period before deposition.
Reesa
Reesa is a monotypic genus of skin beetles (Dermestidae) established by Beal in 1967. The sole species, Reesa vespulae, is a small beetle native to North America that has become a widespread invasive pest of heritage collections and stored products. The species is obligately parthenogenetic—only females are known—and can establish populations from a single individual. Genetic research suggests close relationship to Trogoderma angustum and South American species, with some authors proposing merger into Eurhopalus, though this remains disputed.
Rhopalosiphum
Cherry-Grass Aphids
Rhopalosiphum is a genus of aphids in the family Aphididae comprising approximately 16-17 species worldwide. Species within this genus are significant agricultural pests, feeding on phloem of host plants and causing direct damage to crops. Several species, notably Rhopalosiphum padi (bird cherry-oat aphid) and Rhopalosiphum maidis (corn leaf aphid), are important vectors of plant viruses including barley yellow dwarf virus and maize dwarf mosaic virus. The genus exhibits typical aphid characteristics including polymorphism with both winged and wingless forms, and parthenogenetic reproduction in favorable conditions.
Rhopalosiphum maidis
Corn Leaf Aphid, Corn Aphid
Rhopalosiphum maidis is a globally distributed aphid species and the most economically damaging aphid pest of maize (Zea mays), particularly in tropical and warmer temperate regions. It feeds on phloem sap and causes direct damage through photoassimilate removal. Dense populations can deposit large amounts of honeydew on maize tassels, preventing pollen shed and reducing yield by up to 90%. The species transmits several destructive plant viruses including Maize yellow dwarf virus, Barley yellow dwarf virus, Sugarcane mosaic virus, and Cucumber mosaic virus. Most populations reproduce parthenogenetically (anholocyclic), though sexual reproduction has been reported in Pakistan and Korea with Prunus species as primary hosts.
Schizaphis graminum
greenbug, wheat aphid, common wheat-louse
Schizaphis graminum, commonly known as the greenbug or wheat aphid, is a small aphid species in the family Aphididae. Native to the Palaearctic region, it has been introduced worldwide and is a significant pest of cereal crops, particularly wheat and sorghum. The species exhibits wing dimorphism, with wingless forms predominating early in the season and winged forms developing under crowded conditions to disperse to new hosts. It causes direct damage through feeding and toxin injection, and indirect damage as a vector of multiple plant viruses.
Sciaphilus asperatus
Scaly strawberry weevil, Strawberry root weevil
A wingless, parthenogenetic weevil with a broad Palaearctic distribution, recently introduced to North America. Adults feed on leaves of diverse plants, producing distinctive notched edges, while larvae develop underground on roots. The species exhibits high reproductive output and can form locally abundant populations.
Selenothrips rubrocinctus
redbanded thrips, cacao thrips, red-banded thrips
Selenothrips rubrocinctus is a small thrips species known as the redbanded thrips, recognized by the distinctive red banding on its dark body. It is a polyphagous pest with a near pan-tropical distribution, first described from the West Indies though possibly originating in northern South America. The species is economically significant as a pest of cacao, mango, cashew, and various ornamental trees, causing leaf silvering, distortion, and fruit damage through sap-feeding. Populations exhibit seasonal dynamics tied to host plant water stress and nutritional status, with peaks typically occurring during dry seasons.
Simocephalus
water flea
Simocephalus is a genus of freshwater cladoceran crustaceans commonly known as water fleas. Members exhibit the characteristic cladoceran life cycle with alternating parthenogenetic and sexual reproduction phases. The genus has been studied extensively for reproductive biology, with environmental factors such as temperature, food concentration, crowding, and illumination influencing life history traits.
Sipha
yellow sugarcane aphid (for S. flava), hedgehog grain aphid (for S. maydis)
Sipha is a genus of aphids (Aphididae) in the tribe Siphini, with nearly cosmopolitan distribution. The genus includes notable agricultural pests, particularly Sipha flava (yellow sugarcane aphid) and Sipha maydis (hedgehog grain aphid). Species in this genus feed on grasses and cereal crops, with some capable of transmitting plant viruses such as barley yellow dwarf virus. Several species have expanded their ranges rapidly in recent decades, becoming significant pests of sorghum, sugarcane, wheat, and barley.
Sipha flava
yellow sugarcane aphid
Sipha flava, commonly known as the yellow sugarcane aphid, is a significant agricultural pest native to North America that has spread to multiple continents. This aphid feeds on warm- and cool-season grasses including sugarcane, sorghum, corn, rice, and numerous pasture grasses. It is distinguished by its bright lemon-yellow to pale green coloration, body covered with small spines, and two double rows of dark spots on the dorsum. The species is notable for injecting a toxin while feeding that causes host plant leaves to turn purple in seedlings and yellow to reddish in older plants, leading to stunted growth, delayed maturity, and potential lodging. Unlike many aphids, it produces little to no honeydew. Populations can increase rapidly through parthenogenetic reproduction, with females giving birth to live young for approximately 28 days.
Sipha maydis
Hedgehog Grain Aphid
Sipha maydis, commonly known as the hedgehog grain aphid, is a globally distributed pest of cereal crops and wild grasses. Native to Europe, Asia, Africa, and the Middle East, it was first detected in the United States in 2007 and has since expanded across the Southwest and Rocky Mountain states. The aphid feeds on phloem of Poaceae, with documented hosts including wheat, barley, sorghum, millet, and over 50 plant species worldwide. It reproduces parthenogenetically, with optimal development at 20–25°C. S. maydis is a vector of barley yellow dwarf virus and can cause leaf yellowing, rolling, and desiccation leading to yield reduction.
Siricinae
horntails, wood wasps
Siricinae is a subfamily of wood-boring wasps within Siricidae, commonly known as horntails. Members possess a distinctive elongated, cylindrical body and a prominent spine-like ovipositor at the tip of the abdomen. Females bore into wood to lay eggs, and larvae develop within timber, feeding on fungal symbionts. The subfamily includes the genus *Sirix*, among others.
Sitobion avenae
English Grain Aphid
Sitobion avenae, the English grain aphid, is a globally distributed pest of cereal crops. It feeds on phloem sap and transmits yellow dwarf viruses to wheat, barley, and oats. Population dynamics are influenced by temperature, water availability, and host plant quality. The species exhibits complex reproductive strategies including both cyclical and obligate parthenogenesis. Management challenges include insecticide resistance, variable biotypes, and climate change impacts on dispersal and adaptation.
Sphecophaga
Sphecophaga is a genus of ichneumonid wasps specialized as ectoparasitoids of vespid wasps. Species within this genus parasitize nests of social wasps, with larvae feeding externally on immature wasp pupae. The genus exhibits complex polymorphism in adult forms and cocoon types, and has been widely introduced as a biological control agent for invasive Vespula wasp species. Two recognized species occur: S. orientalis parasitizing Vespa orientalis in the Mediterranean region, and S. vesparum with subspecies in Europe and North America targeting Vespula species.
Sphecophaga vesparum
Sphecophaga vesparum is an ichneumonid ectoparasitoid of vespid wasps, primarily targeting Vespula vulgaris and Vespula germanica. The species exhibits remarkable developmental plasticity with two adult female morphs: large winged females and small brachypterous females, each emerging from distinct cocoon types. It has been introduced to New Zealand and Australia as a biological control agent for invasive social wasps. The species is facultatively deuterotokous, producing mostly parthenogenetic females with occasional males.
Spinibdella
snout mites
Spinibdella is a genus of predatory snout mites in the family Bdellidae, characterized by an elongated rostrum used to pierce prey. The genus has been recorded from soil, leaf litter, and bird nests across multiple continents. Species such as S. bifurcata exhibit parthenogenetic reproduction and complete multiple generations annually. Spinibdella species are active predators with documented preference for psocopteran prey.
Stenochrus
short-tailed whipscorpions
Stenochrus is a genus of hubbardiid short-tailed whipscorpions (order Schizomida) first described by Ralph Vary Chamberlin in 1922. The genus was historically considered a 'junkyard' taxon containing morphologically disparate species, but integrative systematics using molecular and morphological data has redefined its boundaries. As currently circumscribed, Stenochrus comprises approximately ten species distributed primarily in Mexico, Central America, and the Caribbean. The most widespread species, Stenochrus portoricensis, exhibits exceptional geographic range due to parthenogenetic reproduction and ecological tolerance, with introduced populations established in South America and Europe.
Stenochrus portoricensis
short-tailed whipscorpion, microwhipscorpion
Stenochrus portoricensis is a widely distributed short-tailed whipscorpion (Schizomida: Hubbardiidae) native to the Neotropics and Nearctic regions. The species exhibits exceptional dispersal capability facilitated by parthenogenetic reproduction, enabling establishment in diverse habitats across multiple continents. Molecular studies indicate the species is paraphyletic, with a Mesoamerican origin and multiple independent introductions to Europe and the Caribbean from the Yucatán Peninsula. Sexual populations persist in natural habitats across Cuba, Dominican Republic, Guatemala, Mexico, Nicaragua, and Puerto Rico, while parthenogenetic lineages dominate introduced ranges.
Sternorrhyncha
plant-parasitic hemipterans
Sternorrhyncha is a suborder of Hemiptera containing aphids, whiteflies, scale insects, and psyllids—groups formerly classified in the obsolete order 'Homoptera'. The name refers to the rearward position of the mouthparts relative to the head. All members are obligate plant-feeders with piercing-sucking mouthparts adapted for extracting phloem or xylem sap. Many species exhibit highly modified life cycles including parthenogenesis, sexual dimorphism, flightless morphs, and eusociality. The group includes numerous economically important agricultural and horticultural pests.
Stigmella microtheriella
Hazel leaf miner moth, Hazel Leafminer Moth
Stigmella microtheriella is a minute leaf-mining moth in the family Nepticulidae, with a wingspan of only 3–4 mm. The species is native to Europe and Asia, and was introduced to New Zealand from Britain between 1850 and 1860, likely via imported hazel trees. Its larvae create distinctive narrow, angular mines in the leaves of hazel (Corylus species) and hornbeams (Carpinus species). Adults are parthenogenetic and fly in May and August.
Stimulopalpus japonicus
Japanese barklouse
Stimulopalpus japonicus is a tropical barklouse species in the family Amphientomidae, first described by Günther Enderlein in 1906. Males have never been documented, suggesting females may reproduce via thelytoky (parthenogenesis). The species is native to Japan but has established populations across East Asia, South Asia, and as an introduced species in the United States (since the 1940s) and Italy. It is frequently observed aggregating on rocks and concrete surfaces.
Strophosoma
Strophosoma is a genus of weevils (Curculionidae: Entiminae) established by Billberg in 1820. The genus includes both bisexual and parthenogenetic species, with documented variation in reproductive mode between species such as S. capitatum (bisexual) and S. melanogrammum (parthenogenetic). These weevils are known to occur in forest habitats, where some species have been reported as pests in young forest stands. The genus has been subject to taxonomic revision, with subgenera Leucostrophus and Morphostrophus distinguished by morphological characters.
Strophosoma melanogrammum
Nut Leaf Weevil
Strophosoma melanogrammum is a parthenogenetic weevil species native to Europe and introduced to North America. It is one of the most common Strophosoma species in Europe and has been studied extensively for its reproductive biology and association with Wolbachia endosymbionts. The species reproduces through parthenogenesis, with all-female populations, and is known as a pest in young forest stands.
Strumigenys
Mustache and Pygmy Snapping Ants
Strumigenys is a hyperdiverse genus of small predatory ants in the subfamily Myrmicinae, comprising over 880 species. Members are characterized by specialized mandible morphology ranging from gripping to trap-jaw mechanisms, and cryptic lifestyles primarily in leaf litter and soil habitats. The genus exhibits remarkable diversity in nesting strategies, including solitary nesting, xenobiosis, and social parasitism. Several species reproduce via thelytokous parthenogenesis, a rare trait among ants that facilitates colonization of new environments.
Strumigenys membranifera
Bare Mustache Ant
Strumigenys membranifera is a minute trap-jaw ant species native to the Old World tropics that has become a globally distributed tramp species. It is one of only six known Strumigenys species exhibiting thelytokous parthenogenesis, where virgin queens produce diploid female offspring from unfertilized eggs without sperm involvement. Queens retain a functional spermatheca and complete reproductive system despite rarely mating, with males produced only exceptionally. The species has been recorded from numerous regions including Taiwan, Greece (Crete), the Galápagos Islands, and across Asia, reflecting its capacity for human-mediated dispersal and establishment in new environments without mating requirements.
Strumigenys rogeri
Roger's Pygmy Snapping Ant
Strumigenys rogeri is a small dacetine ant species first described by Emery in 1890. It is notable for exhibiting thelytokous parthenogenesis in Taiwan, where virgin queens produce female offspring without mating. This reproductive mode, combined with a short development time of approximately 39 days, may contribute to its success as a tramp ant species. The species belongs to a genus of over 850 species characterized by distinctive trap-jaw mandibles.
Taeniopoda eques
western horse lubber grasshopper, horse lubber
Taeniopoda eques is a large, flightless lubber grasshopper endemic to the Chihuahuan Desert and adjacent arid regions of the southwestern United States and Mexico. Adults are notable for their aposematic black coloration with yellow markings, though color morphs vary geographically. The species is chemically defended against vertebrate predators and uses behavioral thermoregulation to accelerate development in its short growing season. It is univoltine, with eggs undergoing diapause through winter before hatching with summer rains.
Tanytarsus
non-biting midge
Tanytarsus is a large genus of non-biting midges comprising over 480 described species. The genus belongs to the tribe Tanytarsini within the subfamily Chironominae. Larvae occur in diverse freshwater habitats, with some species inhabiting marine environments. Species-level studies reveal complex life cycles with photoperiod and temperature as key determinants of seasonal patterns.
Tetranychus urticae
twospotted spider mite, two-spotted spider mite, red spider mite
Tetranychus urticae, the twospotted spider mite, is a minute phytophagous mite and among the most destructive agricultural pests worldwide. Adults measure approximately 0.4 mm and are typically pale green for most of the year, turning red in later generations. The species is extremely polyphagous, feeding on over 1,100 plant species across 140 families. It reproduces through arrhenotokous parthenogenesis, with females emerging from fertilized eggs and males from unfertilized eggs. Populations can increase explosively under hot, dry conditions, expanding 70-fold in as few as six days. The species exhibits the highest frequency of pesticide resistance among arthropods and was the first chelicerate to have its genome fully sequenced (2011).
Tetrastichinae
Tetrastichinae is one of the largest subfamilies of Eulophidae, containing over 100 genera and nearly 3,000 species of minute chalcid wasps. Members exhibit exceptionally diverse biology: most are parasitoids attacking hosts across 10 insect orders and over 100 families, including nematodes, mites, and spider eggs. Some species are phytophagous (typically as inquilines in galls), gall formers, or inquilines. Endoparasitism predominates over ectoparasitism, with both solitary and gregarious forms known; gregarious species may produce over 2,000 individuals from a single host. Reproduction is often by thelytokous parthenogenesis, though arrhenotoky occurs in some taxa.
Thesprotia graminis
American grass mantis, grass-like mantis
Thesprotia graminis is a small, cryptic mantid native to the southeastern United States. It exhibits remarkable camouflage resembling pine needles or grass blades, achieved through both coloration and posture. The species is notable as the only member of its genus occurring outside South America. It can reproduce both sexually and parthenogenetically.
cryptic-colorationparthenogenesissexual-dimorphismwing-dimorphismgrass-mimicrypine-needle-mimicrysoutheastern-US-endemichemimetabolousoothecabeneficial-insectThespidaemantodeapredatorycamouflage-behaviorpronotum-elongatesingle-dorsal-spine-forelegnon-feeding-first-instarpseudo-iteroparous-reproductionsemelparous-with-multiple-oothecaetympana-present-(unstudied)sexual-cannibalism-unknownThrips
thrips
Thrips is a genus of minute insects in the order Thysanoptera, characterized by fringed wings and asymmetrical mouthparts. Members are typically 1 mm or less in length with slender, cigar-shaped bodies. The genus was established by Linnaeus in 1758 and is among the most economically significant thrips genera, containing species that are serious agricultural pests. Species-level identification is challenging due to morphological variability and reliance on slide-mounted specimens.
Thrips tabaci
onion thrips, potato thrips, tobacco thrips, cotton seedling thrips, tomato thrips
Thrips tabaci is a minute agricultural pest thrips species known by multiple common names reflecting its broad host range. Adults measure 1–1.3 mm and exhibit highly female-biased sex ratios in many populations, with reproduction primarily by parthenogenesis. The species causes direct damage through rasping-sucking feeding and serves as a vector for multiple plant viruses including tomato spotted wilt virus and iris yellow spot virus. It is considered the most serious insect pest of onion crops in tropical regions and has achieved global distribution.
Timema
Timemas
Timema is a genus of small, wingless stick insects representing the sole extant member of the family Timematidae and suborder Timematodea. Native to mountainous regions of western North America, these insects are considered the sister group to all other stick insects, making them evolutionarily significant as a basal lineage. The genus exhibits remarkable diversity in reproductive mode, with five of twenty-one species being parthenogenetic, including two species that have reproduced asexually for over one million years—the longest known asexual period for any insect. Timema species display sophisticated cryptic coloration matching their host plants, with color morphs including green, gray, brown, and striped variants that have been extensively studied as models for ecological speciation and natural selection.
Timema genevievae
Genevieve's Timema
Timema genevievae is a species of walkingstick insect in the family Timematidae. It is one of several Timema species known for reproducing asexually via parthenogenesis. The species is endemic to California. Like other members of its genus, it exhibits cryptic coloration that provides camouflage against host plants.
Timematidae
Timematidae is a family of small, stout-bodied stick insects comprising the single genus Timema. These insects are native to western North America and represent one of the earliest-diverging lineages of Phasmida. They are notable for their relatively short, compact bodies compared to the elongated forms typical of most stick insects.
Toumeyella liriodendri
tuliptree scale
Toumeyella liriodendri, the tuliptree scale, is a soft scale insect (Coccidae) native to North America and specialized on Liriodendron tulipifera (tuliptree or yellow-poplar). This univoltine species overwinters as second-instar nymphs on twigs, matures to adults in spring, and produces eggs that hatch into crawlers in early summer. First-instar nymphs feed on leaf undersides before migrating back to twigs in autumn. Males are unknown; reproduction is presumed parthenogenetic. Heavy infestations cause branch dieback, reduced growth, and honeydew production that supports sooty mold growth. The species has been the subject of recent genomic research, with a 536Mb genome assembly revealing it as an early-diverging soft scale with 17 chromosomes.
Toumeyella parvicornis
pine tortoise scale
Toumeyella parvicornis is a soft scale insect in the family Coccidae, commonly known as the pine tortoise scale. Native to North America, it has become a serious invasive pest in Mediterranean Europe, particularly damaging stone pine (Pinus pinea) forests in Italy and France since its detection in 2015. Mature females are distinctive for their glossy reddish-brown, dome-shaped bodies resembling tiny tortoises, measuring 4–5 mm long. The species has a wide host range among pine species and reproduces parthenogenetically—males have never been recorded. Heavy infestations cause tree weakening, defoliation, and potential death through phloem feeding, with secondary impacts including sooty mold growth on honeydew excretions and altered fire behavior in affected forests.