This soft bug was found in the wet soil under the rotten leaves of the roof garden at home. It doesn't like to move. What's its name? Beneficial insects or pests?

Is this food? It is the larva of scarab, also known as white mud silkworm and walnut worm. Adults are often called scarabs or scarabs. It not only harms Lipu taro, but also harms many kinds of vegetables. According to their feeding habits, they can be divided into three categories: phytophagy, fecal feeding and saprophytic feeding. Among them, herbivorous grubs have a wide range of feeding habits, which are harmful to many crops, cash crops and flower seedlings. They like to eat seeds, roots, tubers and seedlings that have just been sown. They are worldwide underground pests and do great harm. In addition, some kinds of grubs can be used as medicine and are beneficial to human beings.

Appearance characteristics: grub body is hypertrophy, and its shape is bent into C-shape, mostly white, and a few are yellow-white. The head is brown, the upper jaw is prominent and the abdomen is swollen. The body wall is soft and wrinkled, and the body surface is sparse. The head is large and round, mostly yellow-brown, with symmetrical bristles, and the number of bristles is often the characteristic of species classification. For example, there are 3 pairs of big black gill scarab larvae in North China and 5 pairs of yellow brown scarab larvae. Grubs have three pairs of chest feet, and generally the hind feet are longer. Abdominal segment 10, segment 10 is called gluteal segment, and there are bristles on gluteal segment. The number and arrangement of bristles are also important features of species classification.

Living habits: grub generation 1 one to two years. Larvae and adult overwinter in the soil, and adult scarab hides in the soil during the day and feeds at 8-9 pm. Grubs have suspended animation and negative phototropism, and they are addicted to immature feces. Adults lay eggs 10- 15 days after mating, which are produced in soft and moist soil, with the most irrigated land, and each female can lay eggs 100. Hide in the soil during the day and feed at 8-9 pm. Grubs always move underground, which is closely related to soil temperature and humidity. When the soil temperature of 10 cm reaches 5℃, the soil surface layer begins to rise, and the activity reaches the peak at 13- 18℃, and moves to the deep soil above 23℃, and then moves to the upper soil when the soil temperature drops to a suitable range in autumn. Therefore, grubs do the most serious harm to orchard nurseries, seedlings and other crops in spring and autumn. Soil moisture activity is strengthened, especially in continuous rainy weather, which moves in the surface soil in spring and autumn and reaches the surface soil in the early morning and night of summer. ? Occurrence law

Adults lay eggs 10- 15 days after mating, which are produced in soft and moist soil, with the most irrigated land, and each female can lay eggs 100. The age of grubs varies with species and places. This is an insect with a long life history, usually one generation a year, or 2-3 years 1 generation, 5-6 years 1 generation. For example, there are 1 generation scarabs in two years, 1 generation scarabs and scarabs in one year, 1 generation scarabs in Xiaoyun, Qinghai for four years, and 1 generation scarabs in Ganzi, Sichuan for five to six years. Grubs are 3 years old. 1 and 2 are younger, and 3 is the oldest.

There are many kinds of grubs. In the same area and plot, several kinds of grubs often occur together, with overlapping generations, and the occurrence period and damage period are very inconsistent. Therefore, only on the basis of a general understanding of the insect situation, according to the species, density and planting methods of grubs and adults, the corresponding comprehensive control measures can be taken according to local conditions and time, and the effect can be achieved.

① Make a good prediction. Investigate the peak period of adult occurrence and take measures to prevent it in time.

② Agricultural control. Implement paddy-upland rotation; Irrigation in time during corn growth; Do not apply immature organic fertilizer; Intensive cultivation, timely soil suppression, field weeding; Plow the land in a large area in the spring and autumn, and pick insects with plows. In severe areas, overwintering larvae can be turned over in autumn and winter to dry, freeze to death or be preyed by natural enemies, and the control effect of mechanical killing is obvious; At the same time, it is necessary to prevent the use of immature organic fertilizer to prevent adults from laying eggs.

③ Treating the soil with chemicals. 200-250g of 50% phoxim EC per mu, 65,438+00 times of water, sprayed on 25-30kg of fine soil, evenly mixed to make toxic soil, applied along the ridge, and then shallowly hoed, or taken out from the seed ditch or ground, ploughed or mixed with manure for application; Mixing 25-30 kilograms of fine soil with 2-3 kilograms of 2% methyl isofenphos powder per mu to prepare toxic soil; The soil is treated with 3% methyl-isofenphos granules, 3% Weibutan granules, 5% phoxim granules or 5% diazonium granules, with an area of 2.5-3kg per mu.

④ Chemical seed dressing. Seed dressing with 50% phoxim, 50% parathion or 20% isocarbophos, water and seeds according to the ratio of1:30: 400-500; Other underground pests can also be treated by coating with 25% phoxim capsules or 25% parathion capsules or 35% carbofuran seed coating agent with 2% of the seed weight.

⑤ Poison bait trapping and killing. 5 kg of 25% parathion or phoxim capsules 150 ~ 200 g mixed with poisonous bait such as millet, or 3 ~ 4 kg of 50% parathion and 50% phoxim EC mixed with poisonous bait, can also get good control effect when sprinkled in seed ditch.

⑥ Physical methods. In conditional areas, black lights can be set to trap and kill adults, so as to reduce the number of grubs.

⑦ Biological control. Use brown insect-eating flies, scarab black bees, Beauveria bassiana, etc.