近年来,由于气候条件变化异常,加之虫源基数逐年积累,致使土蝗的发生为害逐年加重,据查:1987年还是部分地块发生,到1988年扩展到10万亩,1990年达到了15.7万亩。一般每平方米虫量在10—20头之间,最多的高达250头,轻则将幼苗及叶片吃成缺刻,重则吃成光杆、甚至毁种,产量损失极为严重。 In recent years, due to abnormal climate changes, combined with the accumulation of insect base year after year, resulting in the occurrence of soil locust pests increased year by year, according to the investigation: 1987 or part of the block occurred in 1988 to expand to 10 million mu in 1990 reached 15.7 Mu Insects per square meter generally between 10-20 head, up to 250 head, ranging from the seedlings and leaves eaten into nicks, while eating into polished rod, and even destroyed species, yield loss is extremely serious.