Twospotted Spider Mite

T. urticae is extremely small, barely visible with the naked eye as reddish, yellow or black spots on plants; the adult females measure about 0.4 mm (0.016 in) long. Adult mites sometimes spin a fine web on and under leaves.

T. urticae was originally native only to Eurasia, but has acquired a cosmopolitan distribution as a common pest in a wide range of agricultural systems.

This spider mite is extremely polyphagous; it can feed on hundreds of plants, including most vegetables and food crops – such as peppers, tomatoes, potatoes, pepinos, beans, maize, and strawberries, and ornamental plants such as roses. It is the most prevalent pest of Withania somnifera in India. It lays its eggs on the leaves, and it poses a threat to host plants by sucking cell contents from the leaves cell by cell, leaving tiny pale spots or scars where the green epidermal cells have been destroyed. Although the individual lesions are very small, attack by hundreds or thousands of spider mites can cause thousands of lesions, thus can significantly reduce the photosynthetic capability of plants. They feed on single cells which are pierced with a stylet-like mouthpart and the cell contents are removed, they do damage to the spongy mesophyll, palisade parenchyma, and chloroplasts. T. urticae populations may increase rapidly in hot, dry conditions, expanding to 70 times the original population in as few as six days. The mite's natural predator, Phytoseiulus persimilis, commonly used as a biological control method, is one of many predatory mites which prey mainly or exclusively on spider mites. T. urticae is among the few animals known to synthesise carotenoids. …