Twospotted spider mites are often surrounded in webbing as they build colonies. Heavily infested plants look dirty and covered in webs. Look on lower leaves for initial infestations. Photo by David Cappaert, Michigan State University.
Leaves with heavy stippling is an indication spider mites have been feeding for a long time. Eventually the leaves will turn yellow, then die and fall off the plant prematurely. Photo by Whitney Cranshaw, Colorado State University.
Spider mites have many overlapping generations of adults, nymphs and eggs. Photo by Brian Lang, ISU Field Agronomist.
This photo was taken in Richardson County, Nebraska on 6 July 2012 by Tracy Cameron. He has been monitoring this field for over a month. Spider mites have spread throughout this soybean field and caused discoloration and leaf drop.
Some of you may remember the dreadful summer of 1988, when hot and dry weather ravaged the midwest. Our field crops suffered from a horrible spider mite outbreak and farmers lost a lot of yield. I hope spider mite infestations don't get that bad this year. But it is important to be proactive with this pest and not wait for a field-wide disaster. Read this ICM News article for management information.