Twospotted spider mite adults and eggs

Twospotted Spider Mites

2000. Ralph E. Berry, Department of Entomology, Oregon State University, Corvallis, OR.

Twospotted spider mite, Tetranychus urticae (Acari: Tetranychidae), adults range in size from 0.25 mm to 0.5 mm long. Adults and immature stages are pale yellow or light green with two dark spots on either side of the dorsum. Spider mites feed by disrupting mesophyll cells and sucking up the cell contents, including the chlorophyll. Injured leaves have lower rates of photosynthesis, increased transpiration, and lower chlorophyll content. This injury causes a mottling of the leaves, which may become brown or bronze. A complete life cycle, from egg to adult, may require as few as 14 to 21 days to complete during the summer.

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