Spiny-abdomen
Guides
Gasteracantha cancriformis
Spinybacked Orbweaver, Crab-like Orbweaver, Crab-like Spiny Orbweaver, Smiley Face Spider
Gasteracantha cancriformis is a distinctive orb-weaving spider (family Araneidae) known for its crab-shaped abdomen armed with prominent spines. The species exhibits striking color polymorphism, with females displaying white, yellow, orange, or red coloration combined with black markings. Native to the New World tropics and subtropics, it has been introduced to Hawaii. The species has been extensively studied for its genetic basis of color variation and phylogeographic patterns shaped by Andean uplift and gene flow.
Hystricia abrupta
Spiny-butt fly
Hystricia abrupta is a species of bristle fly in the family Tachinidae, commonly recognized by its spiny abdomen. This large tachinid fly is frequently found in western North America, where adults visit late summer and fall wildflowers for nectar. Like other tachinid flies, it is a parasitoid, with larvae developing inside host insects. It is often mistaken for similar large tachinids such as Adejeania vexatrix and Paradejeania rutilioides due to its robust, spiny appearance.
Macromya
Macromya is a genus of tachinid flies comprising approximately five to seven described species. Members are morphologically similar to one another and closely resemble the genus Adejeania, with which they are frequently confused. The genus reaches its highest diversity in the Neotropics but extends into the southern Nearctic region. Like other tachinids, these flies are parasitoids, though specific host associations remain poorly documented for most species.
Macromya crocata
Macromya crocata is a species of bristle fly in the family Tachinidae. It belongs to the tribe Nemoraeini and was described by Reinhard in 1968. The species is found in North America, where it occurs in forested habitats. Like other tachinid flies, it is a parasitoid, though specific host records for this species remain undocumented. Adults are active during late summer and fall, often observed visiting flowers for nectar.
Micrathena
spiny orbweavers, spiny orb-weavers
Micrathena is a genus of orb-weaver spiders containing over 100 species, predominantly distributed in Neotropical woodlands. Females are characterized by hardened abdomens bearing prominent spines, which have evolved independently at least eight times and function as anti-predator defenses. These spiders construct vertical orb webs and are diurnally active. The genus originated approximately 25 million years ago and has undergone extensive diversification in Andean cloud forests.
Micrathena gracilis
Spined Micrathena
Micrathena gracilis is a small orb-weaving spider in the family Araneidae, commonly known as the Spined Micrathena. Females possess distinctive abdominal spines and build moderately large, tightly coiled orb webs up to 30 cm in diameter. The species exhibits behavioral thermoregulation through web orientation, positioning webs to optimize solar exposure based on microhabitat conditions. It is harmless to humans and primarily inhabits wooded and brushy areas.
Micrathena mitrata
white micrathena
Micrathena mitrata is a small orb-weaving spider in the family Araneidae, commonly known as the white micrathena. Females range from 4 to 9 mm in body length, while males are smaller at 3 to 4 mm. The species is characterized by a shiny black abdomen and spiky, yellowish-brown legs. It constructs circular orb webs to capture flying insects and is found from the United States south to Brazil. Despite its spiny appearance, it poses no danger to humans.
Micrathena sagittata
Arrow-shaped Micrathena, Arrow-shaped Orbweaver
Micrathena sagittata is a small orb-weaving spider in the family Araneidae, recognized by its distinctive arrow-shaped abdomen with prominent spines. Females reach 8-9 mm in body length, while smaller males lack spines entirely. The species constructs circular webs approximately 30 cm in diameter in forest understory vegetation, where it captures flying and jumping insects. It occurs across the eastern United States and Central America, with peak activity from July through September.
Paradejeania
Spiny Tachinid Fly, Hedgehog Fly
Paradejeania is a genus of tachinid flies comprising four described species. The genus is characterized by an exceptionally spiny abdomen, earning species like P. rutilioides the common name "Hedgehog Fly." These are large, robust flies that visit flowers for nectar and function as parasitoids of caterpillars. The genus occurs in western North America, with adults active primarily in late summer and fall.
Paradejeania rutilioides rutilioides
Spiny Tachinid Fly, Hedgehog Fly
Paradejeania rutilioides rutilioides is a large tachinid fly, the nominate subspecies of the Spiny Tachinid Fly. It is distinguished by its robust build, heavily spined abdomen, and subdued orange coloration. Adults are active in late summer and fall, frequently observed visiting flowers. The species is a known parasitoid of caterpillars, specifically documented from Edwards' Glassy-wing moth (Hemihyalea edwardsii).