Wood chips will harm all kinds of plant storage, especially grain and oil. It is the largest and most widely distributed pest in warehouses, distributed all over the country.
Morphological characteristics of (1)
Rice weevil and corn weevil are similar in appearance and are usually controlled as a species in production. Adults are 3.5 ~ 5 mm long, cylindrical, brown or dark brown, with peck-shaped foreheads, and each COLEOPTERA has two yellowish brown oval markings. Larvae is 4.5 ~ 6 mm long, with curved back, no feet, large body, soft and wrinkled. The whole body is milky white, and only the head is pale yellow. The difference between corn weevil and rice weevil mainly lies in reproductive organs. In addition, the corn elephant is wider and fatter, and the rice elephant is thinner and narrower; There are more than 20 carved points along the midline in the front of the corn elephant, while there are less than 20 in the rice elephant. Corn weevil is active, widely distributed, harmful and has a short history of national development.
The adult sawfly is about 2.5 ~ 3.5 mm long, slender, flat, dark brown and dull, and its back is densely covered with yellowish fine hairs. The head is long trapezoidal, the front end is thick and narrow, the surface is rough, and there are small black eyes. There are 6 teeth on both sides of the anterior chest backboard, especially 1 and 6 teeth, and there are 3 obvious longitudinal stripes on the back, which are hairy, with long coleoptile wings and nearly equal sides. Larvae is 4 ~ 4.5 mm long, slender and cylindrical, gray-white, with light brown abdomen and flat head.
(2) Occurrence regularity
Rice weevil and corn can produce several generations a year. Corn weevil can breed not only all year round, but also in the field, while rice weevil can't fly to the field to breed. Corn weevil is superior to rice weevil in low temperature tolerance, hunger tolerance, fecundity and development speed. Corn weevil can overwinter in the warehouse, outside the warehouse and in the gap of loosening soil in the field, while rice weevil can only overwinter indoors. Both larvae can overwinter in grain seeds; Adults are lively and have suspended animation; Eggs are produced in grains, and larvae eat seeds. After eclosion, adults fly out to do harm. Low temperature (below 13℃) and grain water content 10% are not conducive to its growth and development.
Sawgrain thieves can occur for 2 ~ 5 generations every year, mainly wintering under stones and bark near the warehouse, and a few wintering in various gaps in the warehouse. This kind of insect is lively, crawls quickly and rarely flies. Because of its flat body, it is easy to enter the warehouse with loose packaging, causing harm. This insect is very resistant to low temperature, high temperature and chemicals, and it is difficult to control.
(3) Prevention and control methods
Refer to the control methods of wheat moth.