Xiphydria prolongata is a European species that is a wood-borer in small limbs of deciduous tree genera, including Salix L., Quercus L., and numerous Betulaceae (Smith 1983). Larvae generally bore in decaying wood, and are not pestiferous. This western European species was first documented in North America in Michigan and New Jersey in the early 1980s, bringing the known Xiphydria species in North America to nine (Smith 1983). Mudge et al. (2001) recorded the first west coast specimen from Multnomah County, Oregon, in 1989. The single specimen from Washington was found in a trap for Japanese beetle, near Boeing Field in King County (Fig. 3). The specimen is housed at WSDAC.

Figure 3. 

Localities of Xiphydriidae and Diprionidae newly detected in Washington State.

A member of Ross’s (1955)sertifer species group, this species is the only Neodiprion native to Europe, where it is a forestry and nursery pest (Day and Leather 1997). Its primary hosts are Pinus resinosa Aiton and P. sylvestris L., although it will feed on most Pinus species and can be a significant source of damage in pine plantations during outbreak years (Alford 2012). Introduced to New Jersey, USA, in 1925 (Schaffner 1939), its more visible impacts have included feeding damage on Christmas trees, making them less valuable or unmarketable, and defoliation of older needles on ornamental and landscape plants (Wilson 1971). Economic damage in North America has been recorded on P. strobus L., P. sylvestris, and P. mugo Turra, well as several native North American Pinus spp. (Schaffner 1943, Craighead 1950, Benjamin et al. 1955, Griffiths 1959, Baker 1972). Since its introduction, the species has spread westward at least to North Dakota (Van Driesche et al. 2012) and Saskatchewan, Canada (Langor, unpublished data).

Neodiprion sertifer was detected in Washington State in 2008, when citizens in Bellingham, Washington, alerted pest control professionals to several defoliating outbreaks on ornamental pines. Larvae were observed again in 2012 on P. sylvestris and P. mugo in Bellingham, and adult males of Neodiprion sp. were collected in pheromone traps in the city that year. Although the latter were likely N. sertifer, male Neodiprion are not readily identifiable to species using external or genitalic morphology, or by mitochondrial DNA sequences (Linnen and Farrel 2012). Despite extensive surveys in 2010–2013, N. sertifer populations have to date only been found in Washington State within the Bellingham city limits (Fig. 3). The records from Washington State could represent a newer and separate introduction event in the Pacific Northwest, although transport on nursery stock seems to be the most likely introduction pathway. Specimens are housed at WSDAC.

Taeger et al. (2010) list 13 world species of Diprion. Most are Asian, but D. similis is one of two Diprion species native to Europe. Large populations of this solitary feeder occasionally occur in production forestry, often in association with D. pini L., but it is typically not a serious pest (Taeger et al. 1998). The only Diprion recorded from North America (Taeger et al. 2010), D. similis was discovered in New Haven, Connecticut, in 1914, presumably introduced on imported European nursery stock or associated packing materials (Britton 1915). Diprion similis feeds upon multiple pine species, with marked oviposition preference for P. strobus observed in North America (Tsao and Hodson 1956). The species can potentially defoliate entire trees when populations are high; however, this appears to be rare in North America, perhaps due to control by weather events and introduced parasitoids (Wilson 1966, Van Driesche et al. 1996). It is known to occur from the northeastern states westward to the Great Lakes region, and south to North Carolina.

Specimens of D. similis were collected in 2012 when adult females emerged from P. sylvestris boughs collected in Shelton, Washington. Following this detection, yellow card traps were deployed in the south Puget Sound area and Whatcom County. Subsequent visual surveys for larvae were conducted in western Washington. The distinctive larvae are readily recognized, and were found at eight sites in three western Washington counties (Fig. 3). Larvae were most commonly found feeding on P. monticola Douglas ex D. Don, but also on P. sylvestris and P. contorta Douglas ex Loudon. A single male specimen was captured in a Dipion pini pheromone-baited trap, probably by chance since the lure is not known to be attractive across species (O. Anderbrant, in litt.). Voucher specimens are deposited at WSDAC and WWUC.

Gilpinia comprises 37 described species native to Europe and Asia. Gilpinia hercyniae is a solitary spruce feeder, first detected in Ottawa, Ontario, Canada in 1922 and in New Hampshire in 1929 (Baker 1972). It quickly became a forest pest in the eastern United States and Canada (Balch 1939, Reeks and Barter 1951). Ambitious biological control programs during the 1930s imported and released several parasitoid species throughout the region. Concurrent with this, a nuclear polyhedrosis virus was inadvertently released which resulted in consistent region-wide control (Balch and Bird 1944). The species has not been an active management concern in North America for many decades (Nielon and Morris 1964, Kelleher and Hulme 1984). There are no published records of its occurrence west of Manitoba.

A specimen of G. hercyniae was collected in Bellingham in 2008 (although not identified until 2011) from Picea abies (L.) Karst. in a residential neighborhood. Wide-ranging visual and sticky-trap surveys in northwestern Washington failed to detect it beyond the original site, where more specimens were collected in 2011 and 2012 (Fig. 3). Specimens are housed at WWUC and WSDAC.

Heterarthrus is a relatively small genus of leaf-mining sawflies native to Europe and Asia, which generally mine leaves of trees in Aceraceae, Betulaceae, and Salicaceae (Taeger et al. 2010). Two species have been introduced to North America, H. nemoratus and H. vagans (Fallén, 1808), which mine species of Betula L. and Alnus, respectively (Smith 1971, Taeger et al. 1998, Humble 2010). Heterarthrus nemoratus was first collected in North America in Pictou, Nova Scotia, in 1905 (Dowden 1941), and now has a transcontinental distribution in Canada (Digweed et al. 2009). Digweed et al. (2009) review the biology and provide detailed keys to mines, larvae, and adults of this and other birch-feeding Heterarthrinae in North America. The earliest known Washington specimen is a female collected in Whatcom County (the northern-most county in western Washington) in 1967, housed at WWUC. Specimens are also known from the Seattle area (Fig. 7), and the species is likely widespread in western Washington.

Figure 7. 

Localities of Heterarthrinae (Tenthredinidae) newly detected in Washington State.

Heterarthrus vagans was recently detected in North America, discovered in British Columbia in 2009 in numerous locations west of the Cascade Range and very close to the Washington State border (Humble 2010). Visual and sticky trap surveys in 2011 and 2012 detected the species at six sites in Whatcom County (Fig. 7). We have not yet found the species south of Whatcom County, but the widespread distribution of alder makes it likely that this species will continue to spread through Washington and into Oregon. This species’ mines are identifiable by the round cocoon formed in the leaves of its host plants; other Heterarthrus spp. pupate outside of leaves (Humble 2010). Specimens are housed at WSDAC.

Metallus lanceolatus (referenced as M. gei (Brishcke, 1883) in much of the European literature) is a leaf-miner of Geum L. The earliest North American specimens of this Palaearctic species were collected in British Columbia in 1933, and multiple specimens were collected in the northeastern USA and Canada in the 1960s (Smith 1971). Smith (1971) described M. bensoni as a new species from the New York and British Columbia specimens; Koch (1989) subsequently recognized M. bensoni and M. gei as junior synonyms of the Palaearctic M. lanceolatus. Metallus lanceolatus forms coalescing blotch-mines in ornamental and wild Geum, and can be a pest of garden plants (Buhr 1941, Hoebeke and Wheeler 2005). It has apparently spread through southern Puget Sound (Fig. 7), where it was found attacking Geum macrophyllum Willd. in cultivated and wild conditions. Specimens have been hand-collected and captured in Malaise traps. The earliest mines in a large patch of G. macrophyllum near Olympia, Washington, were visible by early July in 2012 and 2013, and could be found on nearly every plant by mid-July of both years. Specimens are housed at WSDAC.

This Palaearctic species is commonly recorded in the literature as Messa nana (see Taeger and Blank 1998 for nomenclatural discussion). Fenusella nana larvae form coalescing blotch mines in many birch species (e.g., Buhr 1941, Taeger et al. 1998, Digweed et al. 2009). The first North American records for this leafminer are from Maine in 1966 (Smith 1967). It has since spread across Canada and into Washington State (Digweed et al. 2009). Digweed et al. (2009) review its biology and provide detailed keys to mines, larvae, and adults of this and other birch-feeding Heterarthrinae in North America. This species has been collected as far southwest as Hoquiam, Grays Harbor County (Fig. 7). Voucher specimens are housed at the NRFC.

The first North American records for this birch leafminer are from Hamden, Connecticut in 1926. It was known from Maine, Ontario, Quebec, and Vermont by the 1960s (Smith 1971), and has since spread across Canada and into Alaska, the Yukon Territory, and Northwest Territories (Digweed and Langor 2004, Digweed et al. 2009, MacQuarrie et al. 2013). It is a significant pest in urban forests (Martin 1960, Drouin and Wong 1984, Snyder et al. 2007). Digweed et al. (2009) review its biology and provide detailed keys to mines, larvae, and adults of this and other birch-feeding Heterarthrinae in North America. The earliest Washington specimen was collected in 1967, in Whatcom County, and was discovered by examining specimens housed at WWUC. Numerous specimens have also been collected south to King County (Fig. 7) and are housed at NRFC.

Profenusa inspirata, a native North American species, is the only known sawfly leaf-miner of oaks in western North America. It creates blotch mines in the upper surface of oak leaves (Fig. 8), that can coalesce when multiple larvae are present in a leaf. The species was previously known from Nevada, California, and Oregon (Smith 1971). Multiple mines were observed in Garry oak (Quercus garryana Douglas ex Hook.) along the Tieton River, Yakima County, and in Skamania and Lewis counties in 2015 (Fig. 7). Larvae were identified using characters described in Smith (1971). Voucher specimens are at WSDAC.

Figure 8. 

Profenusa inspirata mines on Quercus garryana, Yakima County, Washington.

This Palaearctic elm leafminer was already well established in New York by 1898 (Felt 1898), and was certainly introduced with elms from Europe. It is known to attack several elm species, especially Ulmus glabra Huds. and its hybrids (Slingerland 1905, Liston 1993, Scannell 2000); Scannell (2000) added U. pumilla L. and U. davidianaPlanch. to the known elm hosts. Early records of significant damage to U. americana L. seem to be unsubstantiated, with most authors reporting that larvae are unable to do more than initiate feeding (Slingerland 1905, Guries and Smalley 1994, Scannell 2000). Scannell (2000) provided detailed information on the life history and host preferences of this species in the Seattle area. The oldest known west coast specimens were collected in British Columbia in 1947, and are stored in the Canadian National Collection (H. Goulet, pers. comm.). There is anecdotal evidence that the species has been present in Washington since the early 1990s (Scannell 2000), and has since spread south through the Puget Sound area (Fig. 7). Washington State voucher specimens are at WSDAC.

This is an introduced European species that feeds on Galium L (Smith 1969, Taeger et al. 1998). The earliest North America records are 1931 from Cold Spring Harbor, New York, 1933 from Connecticut, and 1934 from New Jersey (Smith 1969). It has since spread to California and the Pacific Northwest. The species is common and was collected as larvae from host plants and readily on yellow sticky traps and in Malaise traps in nearly every county surveyed (Fig. 9). Voucher specimens are at WSDAC.

Figure 9. 

Localities of Blennocampinae, Allantinae, and Tenthredininae (Tenthredinidae) newly detected in Washington State.

A Ranunculus-feeding European introduction, this species has been present in the eastern United States and Canada since the late 1800s and in British Columbia since at least 1919 (Smith 1969). This species is widespread (Fig. 9), and was collected with sticky card traps, Malaise traps, and by hand. The earliest specimens discovered from Washington were collected in Whatcom County in the late 1960s, and were found in the material at WWUC. Numerous species of Ranunculus L. provide suitable hosts in western Washington, including the widespread invasive European weed Ranunculus repens L. Voucher specimens are housed at WWUC and WSDAC.

The genus Eupareophora contains three species, with only E. parca native to North America. It is known from most of the northeastern and central states, and north and west to Alberta (Williams 2007). The species is not known from the Rocky Mountains, but has been collected from several northern California locations and Oregon (Smith 1969). The single historical specimen from Oregon was collected by Koebele, who collected in and around California in the 1880s. Most collection records for this western disjunct population are from California (Smith 1969), suggesting the species may have been native to eastern North America and spread west via human commerce. Williams (2007) similarly suggests that the species was not present in Alberta until the early 2000s. Several Fraxinus L. species are recorded hosts, as well as Carya illinoinensis (Wangenh.) K. Koch (Smith 1969) and Chionanthus L. (Dyar 1898), although Smith (1969) described the latter association as “dubious”. Larvae are readily recognizable by the bristly appearance caused by numerous thick, bifurcate spines. Williams (2007) presented a very detailed account of larval and adult biology in Alberta. Heavy ash defoliation and shed skins of an unknown sawfly were noticed at a public park on the border of King and Snohomish counties in 2014, but no living animals were observed. A return visit in May 2015 found the easily identifiable larvae feeding on Fraxinus latifolia Benth. throughout the park (Fig. 9). Voucher specimens are at WSDAC.

Monostegia abdominalis is a European sawfly pestiferous on Glaux L., Lysimachia L. and Anagallis L. (Price 1970, Taeger et al. 1998). It was first collected in North America in Massachusetts in 1899, and described as M. martini MacGillivray, 1908 (Smith 1979b). In late summer of 2013, noxious weed management staff in King County noticed heavy defoliation of populations of Lysimachia vulgaris L., regulated as a noxious weed in Washington State, by unknown sawfly larvae. Larvae were subsequently collected and reared in the lab on a Lysimachia cultivar in 2014. Specimens are known from several Lysimachia infestations in western Washington (Fig. 9). Voucher specimens are at WSDAC.

This adventive European species was first recorded in North America from Toronto, Ontario, in 1932, from British Columbia in 1934 (Gibson 1980), and later from New York (Hoebeke and Johnson 1985). Larvae feed on Ligustrum L., Syringa L., and Fraxinus (Gibson 1980). A specimen collected in 1977 in Bellingham, Washington, and housed at WWUC is the only record from Washington State (Fig. 9).