Among females with long (4.0–6.0 times as long as high) metatarsomere 2 [areolatus], those of S. longicauda are recognized by the reddish brown tibiae and tarsi. Among males with black metafemur and gena [areolatus, dark form of nigricornis, and dark legged form of nitidus], those of S. longicauda are recognized by the reddish brown protibia and protarsus, the finely pitted vertex, and the widely reddish brown base of the metatibia (brown area about 2.0 times as long as minimum width at base).
Color. Body, antenna, and palps black with dark blue or green metallic reflections. Coxae and femora (except apex) black; tibiae and tarsi reddish brown (Fig. B2.7). Fore wing clear.
Head. Gena with pits 2.0–8.0 pit diameters apart, vertex with pits 2.0–4.0 pit diameters apart, and each pit diameter about 0.16 times lateral ocellus.
Thorax. Mesoscutum with dense pits, each pit round but in median area with numerous transverse ridges. Metatarsomere 2 in lateral view 4.0–5.0 times as long as high; tarsal pad about 0.4 times as long as ventral length of tarsomere. Fore wing vein 3A present and clearly extending along posterior margin of wing.
Abdomen. Median basin of tergum 9 with basal width about 0.72 times as long as median length, maximum width about 0.86 times as long as median length, and median length about 0.63 times as long as cornus length. Cornus in dorsal view long, attenuated in apical 0.25–0.3, and edges not angular midway, its median length 1.42 times as long as maximum width of abdomen at junction of terga 9 and 10. Sheath. Length 1.1–1.4 times fore wing length, basal section 0.4–0.6 times as long as length of apical section. Ovipositor. Lancet with 40–47 annuli (outline of edge of basal annuli difficult to see (Fig. B2.11)); junction of basal and apical section of sheath aligned between 7th and 8th, or 8th and 9th annuli, with about 22 pits beginning near annulus 18. Pits near middle annuli or area at base of apical section of sheath about 0.25 times as long as an annulus (pits gradually decreasing in size toward base), about 0.5 times as high as lancet height in lateral view, and about 1.2 times as long as high; annulus 10 length/ovipositor diameter (lance + lancet) not measured. Last annulus before teeth annuli as well as first tooth annulus with ridge on ventral edge of pit (Fig. C10.3). Edge of apical 9 to 16 annuli before teeth annuli extending as ridge to ventral edge of lancet (Fig. B2.9).
Color. Head, thorax, antenna, palps, abdominal segments 1, 2, 8, sterna 2, 3 and 4 laterally, and 8 black with dark blue metallic reflections; abdominal segments 3–7 (except for black spot laterally on segments 3 and 4) light reddish brown. Coxae, femora, metatibia (except base), and metatarsomeres 1–3 black (Fig. B2.99); tibiae, and tarsi of fore and middle legs, and metatarsomeres 4 and 5 reddish brown (Fig. B2.101); reddish brown spot at base of metatibia large (spot about 2.0 times as long as minimum width of tibia at base) (Fig. B2.99). Fore wing clear.
Thorax. Metatibia 5.5 times as long as maximum width. Metatarsomere 1 in lateral view 4.4 times as long as maximum height.
The type of Sirex longicauda was not examined, but the female description and especially the length of the ovipositor sheath and the long and narrow cornus fits our concept of this species perfectly.
The host range of Sirex longicauda is moderately wide (Middlekauff 1960, Wickman 1964, Cameron 1965). The most preferred hosts (96%) are various species of Abies. Based on 134 reared and confirmed specimens all hosts are Pinaceae: Abies sp. (2), Abies concolor (127) (most records from Kirk (1975)), A. magnifica (1), A. balsamea (1), Pinus sp. (1), P. albicaulis, P. ponderosa, P. strobus (1), and Pseudotsuga menziesii (1).
Based on 29 field-collected and reared (under natural conditions) specimens, the earliest and latest capture dates are from early June to mid October. The main flight period is in late September.
CANADA: BC. USA: CA (Middlekauff 1960), CO, ID, GA, HI, KS (from west coast lumber), NE, NM, OH (from Pinus strobus), OR, UT, VA, WA. Sirex longicauda, a western species, is recorded from southwestern British Columbia to forested regions of California and New Mexico (Fig. C10.4). The four eastern specimens (GA, KS, NE and OH) are probably adventive (Burks 1967, Smith and Schiff 2002).
Specimens studied and included for range map: 46 females and 16 males from BYUC, CNC, OSAC, PFRC, UAIC, UCRC, and USNM.
Specimens for molecular studies: 6 specimens. See Fig. E2.5a.
CANADA. British Columbia: 1982, SIRCA 066, 307. USA. Colorado: 2006, CBHR 914, 658; 2006, CBHR 915, 658; 2006, CBHR 916, 658; 2006, CBHR 917, 658; 2006, CBHR 918, 658.