Tetranychus urticae (common names include red spider mite and twospotted spider mite) is one of many species of plant-feeding mites found in dry environments across the world, and generally considered a pest. It is the most widely known member of the family Tetranychidae or spider mites.
Tetranychus urticae is extremely small, barely visible with the naked eye as reddish or greenish spots on leaves and stems; the adult females measure about 0.4 mm long. The red spider mite, which can be seen in greenhouses and tropical and temperate zones, spins a fine web on and under leaves.
Tetranychus urticae is extremely polyphagous. It can feed on hundreds of plants, including most vegetables and food crops including peppers, tomatoes, potatoes, beans, corn, strawberries; and ornamentals such as roses. 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 and thus can significantly reduce the photosynthetic capability of plants.
The egg of T. urticae is translucent and pearl-like. It hatches into a nymph, which in turn develops into a protonymph, and then a deutonymph, which may display quiescent stages. The adults are typically pale green in colour for most of the year, but later generations are red in colour; mated females survive the winter in diapause.
- ^ a b c D. A. Raworth, D. R. Gillespie, M. Roy & H. M. A. Thistlewood (2002). "Tetranychus urticae Koch, twospotted spider mite (Acari: Tetranychidae)". In Peter G. Mason & John Theodore Huber. Biological Control Programmes in Canada, 1981–2000. CAB International. pp. 259–265. ISBN 9780851995274. http://books.google.co.uk/books?id=tDHWhOEhTckC&pg=PA259.
- ^ a b c d e f Thomas R. Fasulo & H. A. Denmark (December 2009). "Twospotted spider mite". Featured Creatures. University of Florida / Institute of Food and Agricultural Sciences. http://entomology.ifas.ufl.edu/creatures/orn/twospotted_mite.htm. Retrieved May 20, 2011.