Six species of tetranychid mites were found feeding on almond foliage in the southern San Joaquin Valley of California. Two species, the brown mite,Bryobia rubrioculus(Scheuten), and the European red mite,Panonychus ulmi(Koch), were rare. The citrus red mite,Panonychus citri(McGregor), was present on the east side of the valley, annually renewing infestation on almond by ‘ballooning’ from the citrus of that area in spring and dispersing south and west on almond over a period of months. Most of theTetranychusspp. populations sampled were mixed populations consisting of 2 or occasionally 3 species. These 3 principal pest species were not uniformly encountered across the valley. The twospotted spider mite,Tetranychus urticaeKoch, was present in all areas of the valley and was the dominant species in lower elevation mid-valley orchards. The Pacific spider mite,T. pacificusMcGregor, was common or predominant in east and westside foothill orchards above 120 m in elevation and was rare in mid-valley orchards. The strawberry spider mite,T. turkestani(Ugarov and Nikolski) was not encountered in westside orchards and accounted for ¼ to ⅓ of theTetranychuspopulations sampled in mid-valley and eastside orchards.