Sit-and-wait-predator
Guides
Ablautus arnaudi
Ablautus arnaudi is a small species of robber fly in the family Asilidae, first described by Wilcox in 1966. Adults measure approximately 6–7 millimeters in length. The species exhibits sand-colored cryptic coloration and displays distinctive sexual dimorphism in facial hair coloration. Males possess bright white facial hairs and engage in elaborate courtship displays involving leg-waving and rocking movements. Like all Asilidae, this species is predatory in both adult and larval stages.
Asilidaerobber-flypredatorysexual-dimorphismcourtshipearly-springsand-coloredcrypticleafhopper-predatormystaxfacial-hair-dimorphismextra-oral-digestionvenomoussit-and-wait-predatorplains-habitatsmall-size6-7-mmwhite-facial-hairs-malegold-facial-hairs-femaleleg-waving-displayrocking-displayWilcox-1966Ablautus-revisionCharlotte-Herbert-AlbertsColoradoeastern-plainsAchelous spinimanus
Blotched Swimming Crab
Achelous spinimanus is a swimming crab native to the Western Atlantic, ranging from the USA to Brazil. It inhabits coastal marine environments from shallow waters to 90 m depth, with distinct depth preferences between life stages: juveniles occur at 5–35 m while adults are most abundant at 25 m and range to 40 m. The species exhibits continuous year-round reproduction with ovigerous females present in all seasons, and shows seasonal migration patterns in response to water temperature and salinity changes. It is an emerging fishery resource in Brazil, where it has become a target species following declines in more traditional catches.
Andrenosoma fulvicaudum
Northern Chiselmouth
Andrenosoma fulvicaudum is a robber fly (family Asilidae) in the subfamily Laphriinae, distributed across most of North America. Adults measure 15–20 mm and are characterized by distinctive reddish-brown terminal abdominal segments contrasting with blue-black anterior segments. The species is associated with dry, sandy habitats and dead wood, where adults perch on sunlit tree trunks and logs to hunt small insects. Larvae develop as predators of wood-boring beetle larvae.
Badumna
House Spiders, Black House Spider, Grey House Spider
Badumna is a genus of medium to large cribellate spiders in the family Desidae, first described by Tamerlan Thorell in 1890. The genus is native to the Indo-Australian region, with most species endemic to Australasia. Several species, particularly B. longinqua and B. insignis, have become synanthropic and have been introduced to multiple continents, establishing populations in urban environments. The most well-known species, B. insignis, is commonly called the 'black house spider' and has been documented in Japan as an introduced species.
Brachynemurus
antlions
Brachynemurus is a genus of antlions (family Myrmeleontidae, order Neuroptera) containing at least 20 described species. Unlike the pit-digging larvae of the genus Myrmeleon, Brachynemurus larvae are sit-and-wait predators that bury themselves just below the soil surface without constructing funnel traps. The genus is widespread across arid regions of North America, with species adapted to dry environments. Adult Brachynemurus are delicate, lacy-winged insects with short, clubbed antennae that distinguish them from superficially similar damselflies.
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.
Mastophora timuqua
Bolas spider
Mastophora timuqua is an orb-weaver spider in the family Araneidae, notable for its unique hunting strategy. Adult females are bolas spiders that capture prey using sticky silk droplets suspended on a single line rather than constructing a traditional web. The species is known from the United States, with records indicating presence in North America. Like other members of the genus Mastophora, this species exhibits pronounced sexual dimorphism in hunting behavior.
Mecaphesa celer
swift crab spider
Mecaphesa celer is a crab spider in the family Thomisidae, commonly known as the swift crab spider. It is distributed across much of North and Central America. The species exhibits extreme sexual size dimorphism, with females more than twice the size of males. It is a sit-and-wait predator that hunts on flowers and upper plant parts, and has been studied for its population genetics in fragmented volcanic habitats.
Misumenoides formosipes
White-banded Crab Spider
Misumenoides formosipes is a crab spider (family Thomisidae) commonly known as the white-banded crab spider, named for the distinctive white ridge running through the plane of its eyes. The species exhibits pronounced sexual dimorphism, with females significantly larger than males and capable of changing color between white and yellow to match their surroundings, while males maintain a fixed gold coloration with darker front legs. This sit-and-wait predator hunts pollinators on flowers without building webs.
Myrmekiaphila
Ant-loving trapdoor spiders
Myrmekiaphila is a genus of mygalomorph trapdoor spiders in the family Euctenizidae, endemic to the southeastern United States. The genus was first described by G.F. Atkinson in 1886 and has undergone several taxonomic revisions, most recently placed in Euctenizidae in 2012. These spiders construct subterranean silk-lined burrows with silken-soil trap doors, and some species uniquely build side chambers closed by secondary trap doors. The genus name derives from Greek roots meaning 'ant-loving,' referencing their frequent association with ant nests.
Myrmekiaphila comstocki
Comstock's Wafer Trapdoor Spider
Myrmekiaphila comstocki is a trapdoor spider in the family Euctenizidae, commonly known as the wafer-lid trapdoor spiders. It belongs to the infraorder Mygalomorphae, a group of ancient spiders that includes tarantulas and funnel-web spiders. The species constructs silk-lined burrows with hinged, wafer-like trapdoors. Its distribution spans the United States and Mexico.
Myrmeleon
antlion, doodlebug
Myrmeleon is a cosmopolitan genus of antlions in the family Myrmeleontidae, distinguished by larvae that construct conical pitfall traps in sandy substrates. The larvae, commonly called doodlebugs, bury themselves at the bottom of these pits and use specialized mandibles to capture prey that falls in. Adults are delicate, lacy-winged insects resembling damselflies but with short, clubbed antennae. The genus is notable for being one of few antlion genera in North America that exhibits pit-building behavior, and it has been documented across multiple continents including North America, South America, Africa, Asia, and Europe.
Myrmeleon crudelis
antlion
Myrmeleon crudelis is a pit-building antlion species whose larvae construct conical traps in fine-grained soil to capture small arthropods. Research on this species has focused on its behavioral plasticity in trap construction and prey capture kinematics. Larvae demonstrate sophisticated modulation of mandible velocity during strikes and adjust pit architecture in response to prey availability and soil conditions. The species occurs in tropical dry forests of Costa Rica and has been recorded from Middle and North America.
Myrmeleon immaculatus
Doodlebug
Myrmeleon immaculatus is a pit-trapping antlion species in the family Myrmeleontidae. Adults are approximately 30 mm in length and typically blue-grey in color. The species is particularly common in the eastern United States, though its range extends across North America and into Central America. Like other members of the genus Myrmeleon, its larvae construct characteristic conical pits in sandy soil to capture prey.
Myrmeleon mobilis
Myrmeleon mobilis is a pit-making antlion species in the family Myrmeleontidae. The larva constructs conical pits in sandy substrate to trap small ground-dwelling arthropods, using a unique discontinuous gut physiology where solid waste is retained until adulthood. A 2005 microbiological study identified its bacterial associates as primarily Proteobacteria, including Wolbachia-like organisms in non-gut tissues and Enterobacteriaceae-like bacteria in the gut. The species is recorded from North America.
Nannocyrtopogon
Nannocyrtopogon is a genus of robber flies (family Asilidae) comprising at least 20 described species. Members of this genus are aerial predators that capture other insects in flight. The genus was established by Wilcox and Martin in 1936 and is classified within the subfamily Brachyrhopalinae and tribe Ceraturgini. These flies are found in the Nearctic and Neotropical regions.
Nepidae
waterscorpions, water scorpions, water stick insects, needle bugs
Nepidae is a family of exclusively aquatic predatory true bugs containing approximately 250 species in 14 genera. Members are commonly called waterscorpions due to their superficial resemblance to scorpions, possessing raptorial forelegs and a long caudal respiratory siphon. The family is divided into two subfamilies: Nepinae (broad, flat-bodied 'water scorpions') and Ranatrinae (slender 'water stick insects'). They occur on all continents except Antarctica, inhabiting stagnant or slow-moving freshwater habitats.
Pardosa lapidicina
Stone Spider
Pardosa lapidicina, commonly known as the stone spider, is a small wolf spider in the family Lycosidae. It inhabits cobble beaches and rocky shorelines near water, particularly above the tide line. The species exhibits distinctive migration patterns tied to tidal cycles and seasonal temperature changes. Research has documented its use of sit-and-wait foraging behavior combined with sun-basking, and its diet includes small arthropods such as dipterans, collembolans, and amphipods. Males recognize females through a contact sex pheromone located on the female's carapace and legs, requiring physical contact for detection.
Ranatra
water stick-insect, water scorpion, water mantis
Ranatra is a genus of slender aquatic predatory insects in the family Nepidae, commonly called water stick-insects or water scorpions. The genus contains over 140 species distributed across freshwater habitats worldwide, with highest diversity in South America and Asia. These insects are sit-and-wait predators that use raptorial forelegs to capture prey. They possess a distinctive long caudal siphon for breathing while submerged.
Scotoleon
antlions
Scotoleon is a genus of antlions (family Myrmeleontidae, order Neuroptera) containing more than 20 described species. Adult Scotoleon are delicate, slender insects with lacy wings that superficially resemble damselflies but possess short, thick, clubbed antennae. Males frequently exhibit a much longer abdomen tipped with bracket-like claspers. The genus was established by Banks in 1913.
Scotoleon yavapai
Scotoleon yavapai is a species of antlion in the family Myrmeleontidae, first described by Currie in 1903. The genus Scotoleon is distributed across North America, with adults characterized by cryptic coloration and slender, lacy wings. Males of this genus typically possess elongated abdomens with bracket-like claspers. Larvae of Scotoleon species are predatory, burying themselves just below the soil surface to ambush prey rather than constructing pit traps.
Vella
Vella is a genus of antlions in the family Myrmeleontidae, comprising approximately five described species. These are among the largest antlions in North America, with adults reaching wingspans of 100–120 mm or more. Unlike the pit-digging larvae of the genus Myrmeleon, Vella larvae are sit-and-wait predators that bury themselves just below the soil surface without constructing funnel traps. Adults are nocturnal and frequently attracted to artificial lights.