Siricidae
Guides
Eriotremex
Eriotremex is a genus of woodwasps in the family Siricidae (Hymenoptera). Members of this genus are associated with coniferous hosts and are distributed in Asia and North America. At least one species, Eriotremex formosanus, has been introduced to the southeastern United States, where it has been documented in South Carolina. The genus is characterized by morphological features typical of Siricidae, including a cylindrical body and an elongated ovipositor in females.
Eriotremex formosanus
Asian Horntail
Eriotremex formosanus is an Asian horntail wasp (family Siricidae) native to Asia that has been introduced and established in the southeastern United States. Unlike most siricid wasps, which specialize on conifers, this species exhibits unusually broad host associations, utilizing both coniferous and hardwood tree species. Females possess a long ovipositor for drilling into wood and deposit eggs along with fungal symbionts (Amylostereum areolatum) that larvae feed upon during development. The species targets stressed, dying, or recently dead trees rather than healthy timber.
Ibaliidae
ibaliid wasps
The Ibaliidae are a small family of parasitoid wasps in the superfamily Cynipoidea, comprising three extant genera (Ibalia, Heteribalia, and Eileenella) with approximately 20 species worldwide. Unlike most cynipoids, which are phytophagous gall-formers, ibaliids are parasitoids of wood-boring sawfly larvae in the family Siricidae. Adults are notably large for cynipoids, reaching up to 30 mm in length, with a distinctive laterally compressed abdomen. The family is sister to the rest of Cynipoidea excluding the small subfamily Austrocynipidae.
Pseudorhyssa
Pseudorhyssa is a genus of ichneumonid wasps containing cleptoparasitic species that exploit the drill shafts of primary parasitoids to access hosts. The best-studied species, Pseudorhyssa sternata, parasitizes Siricid woodwasps by locating and utilizing oviposition holes made by the primary parasitoid Rhyssa persuasoria. Females detect host-infested trees through stimuli in larval frass, likely associated with symbiotic fungus, and locate specific drill shafts using secretions from the vaginal gland of the primary parasitoid.
Rhyssa howdenorum
Rhyssa howdenorum is an ichneumonid wasp that parasitizes Sirex nigricornis, a siricid woodwasp pest of pine trees. It was described by Townes in 1960 and has been studied in central Louisiana pine plantations. The species has a single generation per year, with adults emerging from infested loblolly pine logs between mid-August and early November. It serves as a biological control agent against its host, which damages pine timber.
Rhyssinae
Rhyssinae is a subfamily of parasitoid wasps within Ichneumonidae, comprising approximately 450 described species across eight genera worldwide. Members are characterized by extremely long ovipositors used by females to drill into wood and parasitize larvae of wood-boring insects, particularly Siricidae (woodwasps) and wood-boring beetles. The subfamily shows highest species diversity in the Oriental region, with significant representation in tropical forests of South America and Africa. Fossil evidence dates the subfamily to the Eocene, approximately 47 million years ago.
Sirex areolatus
Areolate Woodwasp
Sirex areolatus, commonly known as the Areolate Woodwasp, is a species of horntail wasp in the family Siricidae. Like other members of its family, females possess a prominent ovipositor used to deposit eggs into wood, and a shorter dorsal cornus that gives the group its common name. The species has been recorded in parts of Canada including British Columbia and Nova Scotia, with some doubtful records from Europe. As a wood-boring insect, it develops in dead or dying hardwood trees, where larvae feed on wood-rotting fungi introduced by the female during oviposition.
Sirex cyaneus
blue horntail
Sirex cyaneus, commonly known as the blue horntail, is a species of woodwasp in the family Siricidae. Native to forests in Alberta, Canada, adults reach approximately 2 cm in length. The species serves as a host for parasitoid wasps including Rhyssa persuasoria and Ibalia leucospoides, which have been studied for potential biological control applications.
Sirex nigricornis
black-horned woodwasp, native woodwasp
Sirex nigricornis is a native North American woodwasp (family Siricidae) that inhabits pine forests in the eastern United States. Unlike the invasive congener Sirex noctilio, this species primarily attacks stressed, dying, or recently dead pines rather than healthy trees. Females possess a prominent ovipositor for drilling into wood and deposit eggs along with a symbiotic wood-decaying fungus. The species serves as host for multiple parasitoids including the nematode Deladenus proximus, which sterilizes female eggs, and the ichneumonid wasp Rhyssa howdenorum.
Tremecinae
woodwasps, horntails
Tremecinae is a subfamily of woodwasps (Siricidae) distinguished from Siricinae by its association with the white-rot fungus Cerrena unicolor rather than Amylostereum. Unlike Siricinae, which carry symbiotic fungi in specialized mycangia, at least some Tremecinae species lack these structures and do not internally transport fungal symbionts. Females locate host wood already infected with sapwood-decaying fungi using volatile compounds. The subfamily includes forest pests that interact with fungal communities in decaying wood.
Urocerus
horntail, woodwasp
Urocerus is a genus of horntails (woodwasps) in the family Siricidae containing approximately seven to eight described species. These large, non-venomous wasps are characterized by their elongated, cylindrical bodies and prominent cornus (horn-like spine) at the tip of the abdomen. Females possess a long, drill-like ovipositor used to insert eggs into dead, dying, or weakened trees. Species in this genus are obligate mutualists with wood-decaying fungi, which they vector and cultivate for larval nutrition. Several species have broad distributions across the Northern Hemisphere, with some introduced outside their native ranges.
Urocerus cressoni
Black-and-red Horntail
Urocerus cressoni is a large wood-boring wasp in the family Siricidae, commonly known as the Black-and-red Horntail. Females range from 37–50 mm in length, males 18–37 mm. The species is native to North America and has been recorded across Canada from Nova Scotia to Manitoba. Like other horntails, females possess a prominent ovipositor for drilling into wood to deposit eggs, along with a shorter dorsal spine (cornus) that gives the family its common name. The species is non-venomous and poses no threat to humans.
Urocerus flavicornis
Yellow-horned Horntail, Yellow-horned Horntail Wasp
Urocerus flavicornis is a large wood-boring wasp in the family Siricidae, commonly known as the yellow-horned horntail. Native to North America, this species develops inside dead or dying hardwood trees. Adults are active primarily in late summer and fall. The species is non-venomous and poses no threat to humans despite its intimidating appearance.
Urocerus taxodii
Taxodium horntail
Urocerus taxodii is a species of woodwasp in the family Siricidae, described by Ashmead in 1904. As a member of the genus Urocerus, it shares the characteristic elongated, cylindrical body form and prominent cornus (horn-like projection at the abdomen tip) typical of horntails. The species is associated with Taxodium (cypress/bald cypress) as a larval host, as indicated by its specific epithet. Like other siricids, females possess a long ovipositor for drilling into wood to deposit eggs, and they vector wood-decaying fungi that serve as food for their larvae.
Xeris
horntails
Xeris is a genus of horntails (woodwasps) in the family Siricidae, circumscribed by Achille Costa in 1894. The genus contains sixteen recognized species distributed across North America and Eurasia. Xeris species are distinguished from other siricid genera by specific wing venation and morphological features.
Xeris spectrum
wood wasp, horntail
Xeris spectrum is a large horntail or wood wasp in the family Siricidae, notable within its family for lacking the fungal symbionts that other siricid wasps use to aid larval development in wood. Females possess a powerful ovipositor used to drill into coniferous trees and deposit eggs beneath the bark. The species is widespread across Europe, Asia, Africa, and North America, where it develops in the wood of fir, spruce, pine, and larch. Development from egg to adult takes several years, with larvae emerging in two distinct cohorts—some in summer alongside other wood wasps, others the following spring. The species is considered a timber pest due to larval tunneling that degrades wood quality.