Learn about two of the most tenacious summer pests with this guide from the University of Georgia.
Two-spotted spider mite (Tretranychus urticae)
Active: June, July, August
- Adults are about 1/7 mm long, a little larger than a period on a page. They have one oval body segment with eight legs. They are greenish-yellow with a black spot on each side of the body. Eggs are white to yellow. Reddish-orange adult females overwinter in bark cracks.
- Spider mites have a very broad host range. They feed on conifers, deciduous trees and shrubs, as well as herbaceous plants.
- Spider mites suck leaf juices, causing minute white-to-yellow stipples to appear. When large spider mite populations feed, the stipples coalesce and leaves may turn white to yellow to grayish-brown and then die. Some plants are particularly susceptible to spider mite toxins, and even low populations may cause leaves to die.
- Look for early signs of stippling with the beginning of hot summer weather. Examine the underside of damaged leaves or tap them over white paper and look for spider mites with two spots on the body. Also look for predators, such as phytoseiid mites and lady beetles, and note their relative abundance in relation to the number of mites present.
- In dry, hot, sunny locations, this spider mite may produce one generation a week. Use horticultural oil or insecticidal soap sprays for low mite populations to conserve any beneficials present. When damage becomes objectionable, mite populations are high, and there are not beneficials, consider using a residual miticide spray. Reevaluate in one week.
Japanese beetle (Popillia japonica)
Active: June, July, August
- Adults are nearly ½ inch long, broadly oval, thick bodied, with coppery grown wing covers and a metallic green body. Mature larvae are nearly 1 inch long and white, with brown heads. They resemble several other scarab beetle larvae, but may be identified by the shape of the raster (an area of bare spots, hairs, and spines on the underside of the last abdominal segment). There is one generation a year. Larvae overwinter in soil.
- Adults of this imported scarab beetle feed on the flowers and leaves of many plants. Preferred plants include rose, crapemyrtle, maples, sycamore, birch, cottonwood, linden, mountain ash, and elms.
- Look for adults on preferred hosts from early June through August. Weekly application of residual or contact insecticides to host plants in June through July will provide only partial adult control. Traps usually are counterproductive and most often call in more beetles than they trap. Use traps to time insecticide application for adults. Do not use traps for control.