Both sexes probably (female unknown) are recognized by the broadly rounded apex of the fore wing.
Most character states except color of body and microsculpture of sternum 9 should apply to both sexes.
Color. Body, antenna, palps, mandible and legs dark brown and without metallic reflections. Both wings yellow tinted, with extreme apex tinted black (Fig. B1.49).
Head. Median furrow behind ocelli well outlined. Flagellum with 10–11 flagellomeres, and in lateral view middle flagellomeres about 1.5 times as long as high (Fig. B1.55). Head smooth between pits. Gena and lateral area of vertex with pits 0.3–0.5 diameter of lateral ocellus and usually 1.0 pit diameter apart; frons, median section of vertex, and lateral 0.3 of mesoscutellum with pits 0.2–0.3 diameter of lateral ocellus and mainly touching; clypeus with pits 0.2–0.3 diameter of lateral ocellus, generally shallow, and small. Head with long setae.
Thorax. Thorax smooth between pits. Pits about 0.3 diameter of lateral ocellus and less than one pit apart on mesepisternum and metepisternum, net-like on median section of mesoscutum and all of mesoscutellum, and denser laterally on tergum 1. Pronotum with long setae.
Abdomen. Abdomen with pits 0.2–0.3 diameter of lateral ocellus, shallow, and small. Setae on tergum 1 long medially and laterally, on tergum 2 long laterally, on terga 3–8 short and scattered laterally, and on disc of terga 2–8 and sterna 2–9 less dense than elsewhere. Meshes of microsculpture outlined over all terga and sterna of abdomen; posterior 0.5 excluding lateral area of terga 2–8 with pitted sculpticells, followed by clearly raised scale-like sculpticells on most of posterior 0.5 of terga 2–7 and less of tergum 8; terga 1, 2–8 laterally and extreme apex, and sterna 2–9 with flat sculpticells forming weak scales.
It is not clear what a female of this species will look like, but the following characters should help to recognize it when it is eventually discovered: the fore wing shape and the proportion of cell 3R1, and the narrow gena intersected or almost intersected by the outer eye edge in facial view.
The host of S. flammeus is unknown. The species and may be close to Sirex and likely is associated with conifers.
The two field collected specimens were captured on June 19th, 1964.
MEXICO: Durango (Fig. C32.3).
Specimens studied and included for the distribution map: 2 males from CNC.