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The flat mites belong to the family Tenuipalpidae which was described by Berlese in 1913. They are reddish in color, slow moving, and commonly are found feeding on the undersurfaces of leaves, usually near the midrib or veins. The flat mites are also known as false spider mites, a name which hints at their close phylogenetic relationship to the Tetranychidae. Most species of tenuipalpids are not of economic importance, however, all are phytophagous, and the few species that have been identified as pests, have shown that these mites possess the potential to cause severe economic damage to agricultural crops, ornamentals, and timber (Baker 1949, Baker & Tuttle 1987, Ochoa & Salas 1989, Evans et al. 1993).

Flat mites are frequently undetected on plants due to their minute size, flat bodies, and somewhat sessile behavior. Damage caused by these mites is often erroneously attributed to damage caused by fungi, bacteria, nematodes, or nutritional deficiencies. Damage caused by these mites is exacerbated when it is associated with plant pathogens such as rust and greasy spot, and with other arthropods such as thrips, katydids, and peacock mites (Tuckerella) (Ochoa & Salas 1989, Ochoa et al. 1997).

The four most common species known around the world are Brevipalpus phoenicis, B. californicus, B. obovatus, and B. lewisi. These mites feed on leaves, flowers, fruits, and branches. Their feeding damage results in several symptoms such as chlorosis, necrosis, striation of the fruit surface, gall formation and malformation of fruit. These symptoms are well documented (Ochoa et al. 1997, Childers et al. 2003a). The severity of the damage is increased when these mites are associated with viruses. Currently there are four viruses known to be associated with the B. phoenicis "complex" and they include, citrus leprosis virus, coffee ringspot virus, green spot of passion fruit, and orchid fleck virus (Childers et al. 2001, 2003b, Rodrigues et al. 1997, 1999, Kitajima et al. 2000).

The citrus leprosis virus is the most economically important and was described from Argentina in 1941. By 1953, the disease was reported to occur in eight of the northern states of Argentina. In the early 1960s, the disease was reported to occur in other South American countries, including Venezuela and Brazil (Childers et al. 2001, 2003b). Today it is known to occur in all of the major citrus states in Brazil and to cost more than $100 million in control and damage to their crops. Citrus leprosis virus was probably introduced into Panama prior to 1997 but was officially confirmed in 1998 by Brazilian researchers (Childers et al. 2001).

The systematics (biology, ecology, and taxonomic relationships) of the genus Brevipalpus and other genera of flat mites are currently under review. Preliminary indications suggest that morphological characters previously used to distinguish species are poorly understood, are highly variable, and may prove to be inadequate for the separation of species (Welbourn et al. 2003).

The acarologists E. W. Baker and A. E. Pritchard worked extensively on the taxonomy of the Tenuipalpidae during the 1950s, 60s, and 70s. Recently, the SEL has been cooperating with the University of Maryland and the University of Florida to carry out further research on the Tenuipalpidae to improve our understanding of this group of important plant-feeding mites (Childers et al. 2003b, Kane 2003, Welbourn et al. 2003).

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