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Siricidae (Hymenoptera: Symphyta: Siricoidea) of the Western Hemisphere
CJAI 21, July, 2012
doi: 10.3752/cjai.2012.21
Nathan M. Schiff, Henri Goulet, David R. Smith, Caroline Boudreault, A. Dan Wilson, and Brian E. Scheffler

Sirex varipes Walker

Fig. C16.1, Schiff et al. 2006: 54, 55 (female habitus)
Fig. C16.2, Schiff et al. 2006: 53 (male habitus)
Fig. C16.3 (map)

Sirex varipes Walker, 1866: 342. Holotype, female (BMNH, according to Kirby, 1882), not examined. Walker 1873: 78. Burks 1958: 16, Smith 1979: 128. Type locality: Vancouver Island, British Columbia.
Sirex variipes; Dalla Torre, 1894: 393 (unjustified emendation).
Sirex juvencus cyaneus; Konow, 1898: 17, 81, 90, (not Fabricius, 1781: 419).
Sirex cyaneus; Bradley, 1913: 14, (not Fabricius, 1781: 419); accepted by Ries 1951: 83.
Sirex juvencus juvencus x juvencus californicus; Benson, 1962: 252.

Diagnostic Combination

Among females with a light reddish brown metafemur, black abdomen, and long tarsal pad (pad length 0.7–0.8 as long as ventral length of tarsomere) [abietinus, cyaneus and nitidus], almost all those of S. varipes are recognized by the black (with dark blue metallic reflections) longitudinal band along part of or most of the dorsal surface of the metatibia, and usually black on dorsal surface of the protibia and mesotibia. Among males with a reddish brown metafemur and mainly black metatibia [abietinus, cyaneus, nitidus and noctilio], those of S. varipes are recognized by the black surface of most of the mesotibia and almost all of mesotarsomere 1 (often mesotarsomeres 2 and 3 as well) and the very narrow pale base of metatibia (length of pale area shorter than minimum width of tibia at base).



Color. Body, antenna and palps black with dark blue metallic reflections. Coxae and usually tarsomeres 5 black; femora (except brown base) and tarsomeres 1–4 light reddish brown; protibia and mesotibia usually mostly black with dark blue metallic reflections (Fig. B2.72), but in some specimens completely light reddish brown, and metatibia light reddish brown with a dark blue metallic longitudinal band along dorsal surface (black longitudinal band absent in the palest specimens) (Fig. B2.72). Fore wing clear, at most light yellowish brown behind stigma.

Head. Gena with pits 0.0–4.0 pit diameters apart; vertex and postocellar area with pits 0.0–3.0 pit diameters apart, and each pit diameter about 0.1–0.2 that of lateral ocellus.

Thorax. Mesoscutum with few coarse, net-like pits in median area. Metatarsomere 2 in lateral view 3.0–3.6 times as long as high, and its length about 1.1–1.3 times length of tarsomeres 3 + 4; tarsal pad 0.7–0.8 times as long as ventral length of tarsomere. Fore wing vein 3A absent.

Abdomen. Median basin of tergum 9 with basal width 0.9–1.2 times as long as median length, maximum width 1.2–1.5 times as long as median length, and median length 0.55–0.7 times as long as cornus length. Cornus in dorsal view short, with edges straight or slightly rounded in apical third, its median length 0.9–1.3 times as long as maximum width of abdomen at junction of terga 9 and 10. Sheath. Length 0.7–0.85 times as long as fore wing length, basal section 0.9–1.05 times as long as length of apical section. Ovipositor. Lancet with 35–38 annuli (basal 2–4 annuli difficult to see); junction of basal and apical section of sheath aligned between 10th and 11th to 12th and 13th annuli, with 27–31 pits beginning with annuli 3–5. Pits near middle annuli or area at base of apical section of sheath 0.3–0.5 times as long as an annulus (pits gradually and markedly decreasing in size toward base), about 0.5–0.6 times as high as lancet height in lateral view, and 1.5–2.3 times as long as high (Fig. B2.71); annulus 10 length/ovipositor diameter (lance + lancet) not measured. Last 3-5 annuli before teeth annuli as well as first tooth annulus with ridge on ventral edge of pit. Edge of apical 6-8 annuli before teeth annuli extending as ridge to ventral edge of lancet.


Color. Head and thorax black with dark blue metallic reflections. Coxae, mesotibia (at least most of dorsal surface), mesotarsomere 1 (usually mesotarsomeres 2 and 3) (Fig. B2.136), metatibia (except extreme base), and metatarsomeres 1–3 black (Fig. B2.138); femora, protibia and protarsus, at least base of mesotibia, ventral surface of mesotarsomere 1 (in some specimen mesotarsomeres 2 and 3), metatarsomere 4, extreme base of metatibia (spot restricted to minimum constricted portion and less long than wide) (B2.138), and metatarsomere 4 light reddish brown. Fore wing lightly yellowish brown. Abdominal segments 1, 2, and in some specimens basomedian area of terga 3 up to a maximum of terga 3–8 black, remaining segments light reddish brown (Fig. B2.141).

Thorax. Metatibia 3.8–4.5 times as long as maximum width (Fig. B2.138). Metatarsomere 1 in lateral view 2.9–3.8 times as long as maximum height.

Taxonomic Notes

We did not examine the type of Sirex varipes, but the description of the leg color pattern of the female type perfectly matches our concept of this species.

Sirex varipes has been confused with the European S. juvencus (Benson, 1962) and S. torvus. Females of Sirex varipes are easily distinguished from the latter two species by the size and proportions of pits at the middle and base of the ovipositor. Males of Sirex varipes are easily separated from S. juvencus by the color pattern of the middle leg, but are very similar in color to males of S. torvus.

Almost all females of Sirex varipes examined could be correctly identified by metatibial color pattern. However, three females had completely pale metatibia. Such females may be confused with S. cyaneus, S. abietinus and S. nitidus. All four species share a long tarsal pad on metatarsomere 2. However in S. varipes, the ovipositor pit development in apical 0.25 is distinctive and consists of large and long pits.

Hosts and Phenology

Sirex varipes has a wide host range. Based on 27 reared and confirmed specimens, all hosts are Pinaceae: Abies amabilis (10), A. concolor (3), A. grandis (1), A. magnifica (1), A. lasiocarpa (2), Picea englemannii, P. sitchensis (2), Pinus ponderosa (1), Pseudotsuga menziesii (6), and Tsuga heterophylla (1).

Based on 15 field-collected specimens, the main flight period is from early July to early October with a peak in August and September.


CANADA: BC, NS (emerged from western lumber). USA: AZ, CA, MT, NV, IA (wood bed frame), OH (wall probably associated with western lumber), NJ (from wood in home), OR, WA. Sirex varipes, a western species, known from southern British Columbia and southwestern Alberta to south California and Arizona (Fig. C16.3). There are a few records of adventive specimens emerged from lumber in eastern North America (IA, OH, NJ and NS) and Britain (Burks 1967), and we have seen one intercepted specimen from New Zealand (FRNZ). None have become established.

Specimens studied and included for the distribution map: 94 females and 46 males from CNC, MTEC, NFRC, OSAC, PFRC, UAIC, UCRC, and USNM.

Specimens for molecular studies: 20 specimens. See Fig. E2.5e.

CANADA. British Columbia: 2007, CNCS 1046, 621; 2002, SIRCA 054, 639; 2002, SIRCA 055, 630; 1999, SIRCA 068, 384; 1992, SIRCA 070, 348.

USA. California: 2005, CBHR 96, 658; 1999, CBHR 102, 658; 1999, CBHR 104, 658. Idaho: 2008, CBHR 1450, 658. Oregon: 2004, CBHR 223, 658; 2004, CBHR 244, 658; 2001, CBHR 1363, 658; 2001, CBHR 1364, 658. Unknown state: year unknown, CBHR 117, 658; year unknown, CBHR 410, 658; year unknown, CBHR 411, 658; year unknown, CBHR 412, 658; year unknown, CBHR 413, 658. Washington: 2005, CBHR 213, 658; 2005, CBHR 247, 658.