灰飞虱不仅直接为害水稻、大小麦，还是水稻条纹叶枯病、黑条矮缩病的主要媒介。了解灰飞虱在越冬作物大小麦田的分布特证和合适的抽样技术，可以为春季防治灰飞虱从而控制水稻病毒病的发生流行发挥重要作用。为此笔者进行了麦田灰飞虱种群分布调查，并采用扩散型指标法和Iwao回归法测定了浙江北部大小麦田灰飞虱的空间分布型。结果表明：麦田灰飞虱成虫、若虫和成若虫田间分布趋于聚集分布，其聚集原因主要是由灰飞虱生物学特性和环境因素引起的。根据空间分布型的参数，建立了理论抽样数模型为n1=1172.84/ —X +37.46，n2=293.21/ —X +9.36，n3=130.3/ —X +4.16，适用于不同虫口密度下的田间抽样。在每样方虫口密度5、10和15头以上时，分别取样70、40和20个样方。研究结果为准确抽样调查和防治提供了科学依据

The small planthopper Laodelphax striatellus Fallen (Homoptera: Delphacidae) is not only a direct pest of rice, barley and wheat etc., but also a main vector of rice stripe disease and rice black streak disease. Understanding the spatial characteristics of the insect and further developing a sampling technique to estimate its density in the winter crop fields are helpful to make decisions for controlling the planthopper and transmission of the viral diseases. Spatial distribution of the small planthopper population in barley and wheat fields in the Northern Zhejiang province was detected using the dispersal indices and Iwao regression approaches. The results showed that the planthopper populations at the stages of adult, nymph and the pooled nymphs and adults in the sampled fields tended to be in aggregative patterns of spatial distribution. Such pattern were resulted mainly from the planthoppers’ biological characteristics and environmental factors. The theoretical sampling equations were established as:,,, for the adults (n1), nymphs (n2) and adults plus nymphs (n3), respectively. According to the sampling equations, when the density of the planthopper is assumed as 5, 10 and 15 per sampling unit, 70, 40 and 20 sampling units is needed to be sampled.