Spider Mites

Twospotted spider mite injury to eggplantHoneylocust mite bronzing of foliage

Spider mites are common pests on some plants grown in Colorado. Unlike insects, spider mites have eight legs and are smaller than the head of a pin. Getting a look at a spider mite is rare because they are so small and feed on the underside of leaves. Webbing on the plant is an indication of spider mites. These mites suck plant fluids, giving broad-leaved plants a speckled appearance and fading the color of conifers. Spider mites intensify during hot, dry summer days, particularly in July and August.

Twospotted spidermite webbing on ornamental pineHoneylocust spider mites

There are several ways to manage and control spider mites. Natural controls include ladybugs, pirate bugs and other predatory mites. Adequate watering of plants during dry spells is helpful, and hosing plants off with a forceful jet of water can physically remove and kill mites. The use of insecticides, such as Sevin and Malathion, kill the predatory insects that feed on spider mites and Spider Mitestheir use can result in more spider mite outbreaks. Bifenthrin is the only effective chemical control.

Twospotted spidermites and eggs

For more information, see the following Colorado State University Extension fact sheet(s).

For more information, see the following Planttalk Colorado™ script(s).

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Updated Thursday, October 16, 2014