Life patterns of thirty-one spider mite sp.ecies in Japan were observed and categorized in three basic !ife types , including severa! subtypes, using characteristics of spinning behaviour, structure of web as weil as other habits. A little web (LW) !ife type, which in eludes four subtypes was recognized in four genera, namely Aponychus, Eurytetranychus, Panonychus and Yezonychus. Many species of Tetranychus and Eotetranychus, and a few of 0/igonychus, Panonychus and Schizotetranychus are accommodated in a category of complicated web type (CW) , which includes five subtypes. The third !ife type is characterized by a web nest (WN); it has five subtypes, and is found in the genera . Eotetranychus, Schizotetranychus and Oligonychus. It is postulated that the relationship between mite genus and leve! of !ife type complexity agrees with Tetranychinae phylogeny as proposed by GUTIERREZ et al. (1971). Relationships between host plants and spider mite !ife types operating on them indicated that polyphagous mites which live on unstable, annual host plants have only a single !ife type. This may be related to their mode of !ife as r-strategists. The !ife types of mites living on stable host plants, on the other hand, were quite diverse. Significance and problems of classification of !ife types in Tetranychinae, and relationships between the !ife types and !ife histories are also discussed.