The scientific name of this insect is Dolerus tritici Chu, belonging to the family Megachilidae under the order Hymenoptera. It is commonly known as the "Qi headworm" or "small armyworm." This pest is mainly distributed in eastern China, northern China, northeast China, Gansu, Anhui, Jiangsu, and other provinces. The host plants include wheat, barley, and other similar crops. The larvae feed on the leaves, leaving only the veins behind, which causes severe damage to the plant. Morphologically, the female adults measure 8.6–9.8 mm in length, while males are slightly smaller at 8–8.8 mm. The body is black with a slight bluish sheen, and certain parts such as the pronotum, middle thoracic segment, and scutellum are rust red. The wing membrane is transparent yellow, and the head has a reticulate pattern. The base of the labrum is slightly indented, with a large central gap. The antennae have nine segments. The eggs are kidney-shaped, about 1.8 mm long, smooth, and light yellow. The last instar larvae are 18–19 mm long, cylindrical, with a slightly thicker thorax and a thinner abdomen. Each segment has transverse wrinkles. The head is tan, and the upper lip is asymmetrical, with the left side larger than the right. The thorax and abdomen are gray-green, with dark blue on the back. There is one pair of dark spots on the distal part of the abdomen and a single dark marking at the base. The pupa is 9.3 mm long, pale yellowish-white, and turns brownish-black when close to emergence. For control, several methods can be applied. First, agricultural practices such as timely plowing after wheat harvest can help destroy the larvae in the soil. Second, during the larval stage, spraying 90% chlorpyrifos crystals diluted 900 times, 80% dichlorvos diluted 1000–1500 times, or 80% phoxim diluted 2000 times before the third instar is effective. Third, manually collecting dead larvae in the evening can also reduce the population. Fourth, for large fields, applying 2.5% trichlorfon powder or 1.5% dimethoate powder at a rate of 1.5–2.5 kg per 667 m² is recommended. These insecticides can also be mixed with 25 kg of fine soil and applied along the ridges, helping to remove wheat straw and further control the pest. Shandong YingLang Chemical Co.,Ltd , https://www.sdylhgtrade.com
In terms of life habits, this species completes one generation per year and overwinters in the soil. Adults emerge from March to April of the following year. After mating, females use their ovipositor to cut small slits along the main leaf veins for egg-laying. Eggs are laid in clusters, and the egg stage lasts about 10 days. Larvae appear from mid-April to mid-June. During the damaging period, they burrow into the soil during summer and remain in the soil through winter. Adults are most active between 9 AM and 3 PM, but their flying ability is weak. They hide at the roots of wheat and barley during cloudy days or at night. Their lifespan is 2–7 days. The larvae go through five instars. After the third instar, they hide in the lower part of the wheat plants or under clods during the day and feed at night. By the fourth instar, their feeding rate increases rapidly. The larvae have a pseudo-dormant behavior, avoiding dry and hot conditions, and preferring moist environments. Warm winters, adequate soil moisture, and moderate temperatures in late spring, along with light rain in March, all favor the occurrence of this pest.