Abstract: The results are reported in this paper of a faunal and ecological investigation of chigger mites in Dongning and Luobei counties of Heilongjiang province and Helong county of Jilin province during 1980—1983. 1. 15 species belonging to 6 genera of the chigger mites were recorded from the three regions. The predominant species are Neotrombicula pomeranzevi and N.gardellai. The composition of species of chigger mites varies with different habitats, season and hosts. 2. The hosts with higher infested rates by chigger mites are: Clethronomys rutilus, 92.0% and C. rufocanus, 81.3%. Microtus fortis and Eutamias sibiricus have higher infested indices by the mites, which are 22.4 and 21.9 respectively. 3. The seasonal distribution of species of chigger mites are: N. tamiyai and Miyaterombicula escensis found mainly in summer, and N. gardellai, N. microti, N. pomeranzevi and Leptotrombidium zeta in summer-autumn.

Key words: Aphis gossypii, Propylaca japoinica, Spatial distribution, Geostatistics