Spider Mite Tetranychus urticae “Two-Spotted” or “Red Spider Mite”
The two-spotted spider mite or red spider mite is a major pest in vegetables, tropicals, and other ornamentals. It’s tiny size makes it difficult to see. They prefer to feed from the bottom side of leaves located in the tops of plants where it is warm and dry, although as they travel along the plant, feeding marks can be found along the main vein of leaves near the petiole. As populations increase, plant damage spreads across the leaves.

Spider mites feed on plant cells and produce characteristic small, yellowish, speckled feeding marks. The feeding marks are usually the first sign of a mite infestation and are often confused with some fertilizer deficiencies. Fine, silken webs can be detected on heavily infested leaves and flowers with these plant parts quickly withering and turning brown.

Many insecticides have little or no affect in controlling spider mites. Their small size, their ability to exist close to the veins of the plants and because they are a different species of pest than other insects, controlling by spraying is extremely difficult.

Spider mites are sensitive to day length and are capable of diapausing (hibernating) within cracks and crevices of your structure. If you had spider mites last year, chances are excellent they will continue to be a problem this year.

Spider mite populations can explode under conditions of high temperature (above 85° F.) and low relative humidity (below 60% RH).

Spider mite Life Cycle
@ Temperature in oF 60 64 70 90
# of Days (Egg to Adult) 30 21 14.5 3.5


Spider Mite Predators
When predatory mites are used as recommended to control this pest, success is practically guaranteed. These predatory members of the mite family will multiply nearly twice as fast as the spider mite population. Predatory mites only feed on other mites, they do not feed on plants.

Misting systems can help raise the humidity, cool the plants and slow the reproduction of spider mites. High temperature strains of predators are also available.

At an average of 68° F., predatory mites multiply at a weekly rate of approximately 4.6, while spider mites multiply at a weekly rate of approximately 2.7. About four days after a predatory mite egg is laid, it hatches and begins feeding on spider mites.