Two Spotted Spider Mites

Two Spotted Mite Description

The two spotted spider mite is quite small (< 1/60 in.), oval-shaped, has 4 pieces, 7 legs, and is yellowish or greenish with two dark spots on its back which are composed of food contents. Males are slightly smaller (1/80th in.) and slimmer than females with a pointed abdomen. The eggs of the two-spotted spider mite are pearly white, circular, and on the webbing on the foliage. Young mites resemble the adults except in size and possess only 3 pairs of legs in the first stage. Later they develop a fourth pair of 7 legs. The immature mites pass through three stages before becoming adults.

Spider mites can cause extensive damaged leaves. Leaves turn from dark green to pale or bright yellow.

spider mite colony (15034 bytes)

Two spotted mites, eggs (round balls) and adults.

Rose leaf damaged by Spider mites.

Life Cycle

Spider mites attack many species of plants including common greenhouse crops such as tomatoes, carnations, chrysanthemums, snapdragons, violets, roses, and fuchsia. Spider mites may be found on any part of the plant, but most often are on the middle-aged leaves. Under severe infestations, they may be found on the growing tips. Generally, the lower leaf surface is preferred over the upper surface. Egg laying and development is affected by temperature. The optimum temperature for egg laying is 30 degrees C with an individual female laying 100 eggs and living for 30 days. Under these conditions, a new generation is
produced every eight days. Under low temperatures (21 degrees C) development may be slowed taking 14 days for a generation and at 12 degrees C the process may extend to 40 days. Under optimum conditions, a female mite may produce 13 million offspring during her lifetime. Spider mites are most damaging under greenhouse conditions of high temperature and low humidity.

Plant Damage

Damage caused by the two-spotted spider mite will vary according to the infestation level however, mites feed by piercing plant cells with their mouthparts and sucking out the cell contents. Lightly infested plants will have foliage with pale blotches or spots showing through the leaf while with heavy infestations the entire leaf appears light in color, dries up, and often turns a reddish-brown with blotches in and around the edges. Plants generally lose their vigor and die. Silken threads will also be present among the foliage. The mites will be located on the underside of the foliage and appear as tiny, reddish, greenish, yellowish, or blackish, moving dots. The mites' color appear to be related to the type of host plant.