About Zabrus tenebrioides (Goeze, 1777)
Zabrus tenebrioides is a species of black ground beetle belonging to the subfamily Pterostichinae. It can be found throughout Europe and the Near East, and its distribution extends through steppe and forest-steppe regions up to the southern border of Polesia. Based on the species' local abundance and the severity of damage it causes, the territory of Russia can be split into two zones: one where the species causes permanent damage, and one where damage occurs cyclically. Adult beetles measure 12–16 millimetres (0.47–0.63 in) in length, have a resinous black colouration with a weak metallic sheen. Their elytra are convex and marked with deep grooves. The antennae, tibiae and feet are dark brown. The eggs of Zabrus tenebrioides are oval, milky white, and measure 2–2.5 mm across. Mature larvae reach up to 28 mm in total length, and develop through three instars that are distinguished by differences in the size of the head capsule and body. For first instar larvae, the head capsule width is 1.1–1.2 millimetres (0.043–0.047 in); for second instar larvae it is 1.65–1.85 mm; and for third instar larvae it is 2.25–3.1 millimetres (0.089–0.122 in). Body lengths for the three instars are 5–12 mm, 10–20 mm, and 18–28 millimetres (0.20–1.10 in) respectively. The head and thoracic segments of larvae are dark brown. The abdomen of first and second instar larvae, and of mid-stage third instar larvae, is grayish. Larvae that have finished feeding are white, and turn cream-coloured just before pupation. The pupae are of the open type, white in colour, and develop inside an earthen cradle.
