Among females with a black metafemur and metatibia and short metatarsomere 2 (less than 3.0 as long as high) [californicus, mexicanus, nigricornis, obesus and xerophilus] those of S. behrensii are recognized by the reddish brown tarsi and the mainly reddish brown abdomen. Males are recognized by the metafemur with a reddish brown ventral half and a black dorsal half, and by the brown spot on the gena behind the eye and occipital margin.
Color. Head, antenna, palps, thorax, abdominal segments 1 and 2, lateral surface of terga 3–9 or 3–10, and lateral surface of sterna 3–7 or 4–7 black with dark blue metallic reflections; most of terga 3–9, or all of tergum 9 and 10, and most of sterna 3–7 or 4–7 reddish brown (Fig. B2.13). Coxae, femora, most of tibiae, and most of or part of tarsomere 1 of fore leg or fore and middle legs black; apex and ventral half of tibiae, tarsomeres 2–5 of fore leg, 1–5 or 2–5 of middle leg, and metatarsus reddish brown. Fore wing in apical third and basal to stigma with darkly tinted bands (Fig. C6.3).
Head. Gena with pits 4.0–8.0 diameters apart between eye and posterior head margin; very dense on vertex and postocellar area, and each pit diameter about 0.25 times lateral ocellus. Gena with central surface with a round ridge between eye and occiput (Fig. B2.16).
Thorax. Mesoscutum with dense pits in median area; pits round, and transverse ridges moderately numerous. Metatarsomere 2 in lateral view 2.4–3.0 times as long as high; tarsal pad 0.4–0.5 times as long as ventral length of tarsomere. Fore wing vein 3A present and extending to posterior wing margin (Fig. C6.3).
Abdomen. Median basin of tergum 9 with basal width 0.8–1.0 times as long as median length, maximum width 1.1–1.7 times as long as median length, and median length 1.0–1.2 times as long as cornus length. Cornus in dorsal view short, with edges straight or slightly angular midway; its median length 1.0–1.2 as long as maximum width of abdomen at junction of terga 9 and 10. Sheath. Length 0.68–0.82 times fore wing length, basal section 0.93–1.17 times as long as apical section. Ovipositor. Lancet with 31–36 annuli (basal annuli clearly outlined); junction of basal and apical section of sheath aligned between 12th and 13th annuli, with 28–32 pits beginning with annulus 2. Pits near middle annuli or area at base of apical section of sheath, about 0.2 times as long as an annuli (pits gradually decreasing in size and very small toward base), about 0.3 times as high as lancet height in lateral view, and about 1.5 times as long as high (Fig. B2.18); annulus 10 length/ovipositor diameter (lance + lancet) not measured. Last 2-3 annuli before teeth annuli as well as first tooth annulus with ridge on ventral edge of pit. Edge of apical 5-7 annuli before teeth annuli extending as ridge to ventral edge of lancet.
Color. Head (except behind eye), thorax, antenna beyond flagellomere 6, palps, and abdominal segments 1 and 2 black with dark blue metallic reflections; smooth surface on gena between eye and posterior margin of occiput brown (Fig. B2.106); antennomeres 1-5, and abdominal segments 3-9 light reddish brown. Coxae, striated surface of femora of fore and middle legs, and dorsal 0.5 of metafemur black (Fig. B2.104); metatibia (except extreme base), apical 0.3–0.5 of mesotibia and mesotarsomeres 1–2, and metatarsomeres 1–3 and 5 brown to dark brown (Fig. B2.104); most of femora of fore and middle legs, ventral half of metafemur, tibiae and tarsi of fore leg, basal 0.3–0.7 of mesotibia, mesotarsomeres 3–5, metatarsomeres 4, and extreme base (spot about 0.5 times as long as minimum width of tibia at base) of metatibia light reddish brown. Fore wing clear.
Thorax. Metatibia 3.5-4.0 times as long as maximum width (Fig. B2.104). Metatarsomere 1 in lateral 2.7-3.5 times as long as maximum height.
Females of S. behrensii may be confused with the pale abdomen females of S. nigricornis. The clearly outlined banded wing pattern, the broad black longitudinal band along the side of the abdomen and completely reddish brown segment 10, and the presence of fore wing vein 3A should distinguish them from S. nigricornis females. Males are easily distinguished among New World Sirex by antenna and hind leg color patterns. Daly (1963) used specimens of S. behrensii for thoracic muscle studies.
The host range of S. behrensii is moderately wide (Flanders, 1925, Essig 1926, Middlekauff 1960, Cameron 1965). All but one hosts, based on 50 reared and confirmed specimens, are Pinaceae: Pinus Jeffreyi (2), P. lambertiana (1), P. ponderosa (46), P. radiata, and Pseudotsuga menziesii (1). One record is on Cupressus macrocarpa (Cupressaceae).
Based on 30 field-collected specimens, the earliest and latest capture dates are from early June late November. The main flight period is from late July to late October with a peak in late September.
CANADA: BC. USA: CA (Middlekauff 1960), ID, NV, OH (probably not established), OR, WA, WV (probably not established). Sirex behrensii, a western North American species, is recorded from southernmost British Columbia to California and Nevada (Fig. C6.4). The specimen from Ohio was on imported lumber and is probably not established (Smith and Schiff 2002).
Specimens studied and included for range map: 32 females and 38 males from CNC, OSAC, PFRC, UCRC, and USNM.
Specimens for molecular studies: 13 specimens. See Fig. E2.5a.
CANADA. British Columbia: 2002, SIRCA 048, 416; 2002, SIRCA 050, 407; 2002, SIRCA 051, 575; 2002, SIRCA 052, 407. USA. California: 2006, CBHR 664, 658; 2006, CBHR 665, 499; 2006, CBHR 666, 658; 2006, CBHR 667, 658; 2006, CBHR 669, 658. Oregon: 2006, CBHR 1075, 658; 2006, CBHR 1076, 658; 2006, CBHR 1077, 658. Unknown State: unknown year, CBHR 171, 658.