Spider mite infestations of peanuts generally develop during periods of little or no rainfall. Infestations usually originate at points where fields adjoin untended ditch banks, fence rows, or areas having weeds or brush. Severe levels of infestation may cause yellowing or chlorosis and defoliation of plants. Mites in severely infested areas will cover plants with webs of silk, particularly in the uppermost vegetation. Large numbers of mites frequently are seen at the top of these webbed areas, which are launching pads for mite spread by prevailing winds.