一、螻蛄种类与危害的调查(一)种类:掘调查余积公社螻蛄发生的种类主要是华北螻蛄,占95%以上,非洲螻蛄占5%左右。(二)危害与地势土质的关系 螻蛄发生和为害与地势土质有密切关系。余积公社沿河2,745亩砂土地(群众叫砂包地)全部受害,地势比较低洼的砂壤土地和黄土地也受害。从受害地的土质和地势情况可 I. Types and Harm of Wagtail (I) Types: Excavation of Cudgery The commonest occurrences of grubs mainly occur in northern China, accounting for more than 95% of the total, and about 5% of them are in Africa. (B) the relationship between hazards and topography Soil 蝼 蛄 occurrence and damage and the terrain is closely related to soil quality. Yuji Commune along the river 2,745 acres of sandy land (the crowd called sand enclave) all victims, low lying sand land and yellow land also suffered. From the soil and topography of the victim may be