Wheat stem fly

Scientific name Hydrellia chinensis Qi et Li, known as the wheat sheath eyed fly, and Hydrellia griseola Fallen, known as the rice small eyed fly. Both belong to Diptera, Ephydridae. Also known as rice leaf miner, barley water fly, etc. Commonly called sheath miner. Distributed in North China, East China, Northeast China, Gansu, and the wheat regions of Southwest China.

Hosts @#@245@#@, barley, rye, oats, rice, etc.

Damage characteristics: mainly damages the leaf sheaths of the above hosts, with the vast majority damaging the leaf sheaths of the 1-2 leaves below the flag leaf, and a few damaging the leaf blades. When damaging, the larvae bore and mine in the tissue between the inner and outer epidermis of the leaf sheath or leaf blade, forming straight or irregular mines. The mines often contain no obvious frass, and in the later stage only the epidermis remains. This causes the leaves to dry up prematurely, or prevents heading, or results in empty and shriveled grains.

Morphological characteristics: adult body length 2-4 mm, wingspan 5 mm, body color grayish dark, antennae black, with 1 pair of wings, the front edge of the wing with 2 notches, hind wings transformed into halteres, bright red. Egg length 0.7 mm, oval, milky white, the egg surface with longitudinal striations. Mature larva body length 4-4.5 mm, flat cylindrical, pale yellow-white, mouth hooks deep black. Pupa length 4 mm, initially yellowish brown, the posterior end with 2 small black protrusions.

Life habits: 2 generations per year in Gansu, 3-4 generations per year in the wheat regions of Southwest China, overwintering as pupae in the leaf sheaths. In the wheat regions of Southwest China, after adult emergence from February to April of the following year, they first feed on nectar in flowering rapeseed fields to supplement nutrition, and after mating lay eggs on the base of the upper surface of the flag leaf or upper leaves of wheat at the booting to heading stage. Each leaf receives several to more than 10 eggs, with as many as 40-50 eggs. The egg stage is 4-10 days, and the larval stage is 13-19 days. March to April is the larval damage period. Mature larvae pupate in the leaf sheaths in early April, sometimes gathering more than 20 individuals. In northern wheat regions, overwintering-generation adults begin activity in mid-May, mate and lay eggs, larvae begin occurring in early June, enter the peak occurrence period in mid-to-late June, pupate in July, and first-generation adults emerge in mid-July. The second generation lays eggs on weeds or self-sown wheat seedlings, and the larvae damage until late autumn, when they begin to pupate and overwinter. The occurrence of the wheat stem fly is closely related to varietal traits. In production, varieties with tender leaves and deep color, wide and thick leaves, and thick, deeply sunken leaf veins receive more eggs and suffer more severe damage.

Control methods: (1) Select insect-resistant varieties with hard stems and moderate leaves. (2) Carry out forecasting and prediction. When the rate of wheat plants with eggs reaches about 10%, with an average of more than 10 eggs per plant, and the initial hatching stage begins, immediately spray 90% trichlorfon crystal at 1500 times dilution, or 50% fenitrothion emulsifiable concentrate at 1500-2000 times dilution, 36% kelvfly emulsifiable concentrate at 1000-1500 times dilution, or 40% dimethoate emulsifiable concentrate at 2000 times dilution, spraying 75 L of the prepared spray solution per 667 sq m.