Eriotremex formosanus

Distinguished from native North American siricids by its Asian origin and exceptionally broad host range spanning both conifers and hardwoods. Females have a prominent, elongated ovipositor for wood-drilling. Can be separated from the congeneric Eriotremex hastatus by morphological features and geographic distribution. The combination of oviposition into hardwood species and transport of Amylostereum areolatum distinguishes it from most other siricids in its introduced range.

Forested areas containing stressed, dying, or recently dead trees; larval development occurs entirely within the wood of host trees. In its introduced North American range, has been documented in diverse forest types in South Carolina including pine forests, mixed hardwood stands, and riparian areas.

Native to Asia (Taiwan, where first described, and broader Asian range); introduced and established in the southeastern United States, specifically documented in South Carolina with GBIF records indicating presence in the conterminous 48 United States.

Larvae feed exclusively on fungal symbionts (Amylostereum areolatum) cultivated in the wood of host trees; adults do not feed.

• Pinus taeda - hostloblolly pine
• Pinus echinata - hostshortleaf pine
• Pinus palustris - hostlongleaf pine
• Pinus strobus - hosteastern white pine
• Picea rubens - hostred spruce
• Tsuga canadensis - hosteastern hemlock
• Liquidambar styraciflua - hostsweetgum
• Liriodendron tulipifera - hosttulip poplar
• Acer rubrum - hostred maple
• Quercus spp. - hostoak species
• Carya spp. - hosthickory species
• Nyssa sylvatica - hostblack tupelo
• Ulmus spp. - hostelm species
• Celtis laevigata - hostsugarberry/hackberry
• Salix nigra - hostblack willow
• Alnus serrulata - hostsmooth alder
• Betula nigra - hostriver birch
• Fagus grandifolia - hostAmerican beech
• Cercis canadensis - hosteastern redbud
• Cornus florida - hostflowering dogwood
• Sassafras albidum - hostsassafras
• Sambucus nigra - hostelderberry
• Robinia pseudoacacia - hostblack locust
• Gleditsia triacanthos - hosthoney locust
• Juniperus virginiana - hosteastern red cedar
• Chamaecyparis thyoides - hostAtlantic white cedar
• Taxodium distichum - hostbald cypress
• Magnolia grandiflora - hostsouthern magnolia
• Magnolia virginiana - hostsweetbay magnolia
• Laurus nobilis - hostbay laurel
• Persea borbonia - hostredbay
• Ilex opaca - hostAmerican holly
• Ilex vomitoria - hostyaupon
• Myrica cerifera - hostwax myrtle
• Morella rubra - hostred bayberry
• Rhus copallinum - hostwinged sumac
• Rhus typhina - hoststaghorn sumac
• Toxicodendron radicans - hosteastern poison ivy
• Vitis rotundifolia - hostmuscadine grape
• Smilax spp. - hostgreenbrier species
• Lonicera japonica - hostJapanese honeysuckle
• Pueraria montana var. lobata - hostkudzu

Females use their elongated ovipositor to drill into wood of host trees and deposit eggs along with fungal symbiont Amylostereum areolatum carried in specialized intersegmental pouches. Eggs hatch into larvae that tunnel through wood, feeding on the cultivated fungal symbionts. Larvae develop through multiple instars over an extended period. Pupation occurs within the wood, and adults emerge through exit holes. Males likely emerge before females, though specific timing has not been documented.

Females exhibit strong preference for stressed, dying, or recently dead trees rather than healthy trees, a behavior that facilitates detection and colonization of suitable hosts. Oviposition involves drilling into wood with the ovipositor and inoculating the tunnel with fungal symbionts. The species demonstrates unusual behavioral plasticity in host selection, utilizing both coniferous and hardwood species—a breadth uncommon among siricid wasps.

Wood-boring insect contributing to decomposition of dead and dying trees in forest ecosystems. Acts as a vector for the fungal symbiont Amylostereum areolatum, facilitating its spread into new wood substrates. May accelerate wood degradation and nutrient cycling in forests. In its introduced range, represents a potential pest of stressed timber resources and may compete with native wood-boring insects for habitat.

Potential pest of stressed or damaged timber resources in its introduced North American range. The broad host range including commercially valuable hardwood and conifer species raises concerns for forestry operations. No direct economic damage estimates have been published, but its establishment in the southeastern United States represents a novel forest health concern.

• Eriotremex hastatusCongeneric species; distinguished by morphological features and geographic distribution
• Urocerus spp.Native North American siricids that specialize on conifers and do not exhibit the broad hardwood host range of E. formosanus
• Sirex spp.Native North American siricids with more restricted host associations, primarily conifer specialists

• Siricidae
• wood-boring
• invasive species
• fungal symbiont
• forest pest
• Asia
• North America
• South Carolina
• broad host range
• Amylostereum areolatum

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
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