The citrus rust mite (Phyllocoptruta oleivora [Ashmead]), was first described by Ashmead in the Florida Agriculturist in September, 1879. For over 50 years it was the only species of Eriophyid mite reported from citrus. In 1937 the citrus bud mite (Aceria sheldoni [Ewing]) was described from California. This species has recently been found in Florida (Attiah, 1959). Several new species of Eriophyid mites have been collected from citrus during the past few years. These include Calacarus citrifolii Keifer from Union of South Africa (Keifer 1955) ; Aculus pelekassi Keifer from Greece (Keifer 1959a), Thailand (Keifer 1959b), Japan, Italy, and Sicily (Keifer 1962); Floracarus fleschneri Keifer from India (Keifer 1959b); and Diptilomiopus assamica Keifer from India (Keifer 1959b). One of these A. pelekassi, has been found in Florida during the past few months (Denmark, in press). This mite has a distinct pink color in Florida, although Keifer's description reports it as being light yellow in Greece (Keifer, 1959a). Differences in color of citrus rust mites have been observed frequently. Speare and Yothers (1924) noted that adult citrus rust mites may change color from lemon yellow to a darker or orange yellow and reported that these offcolor mites frequently were diseased. They further reported that these mites would congregate in large numbers on the sunny side of fruit where they were observed in a writhing, wriggling mass. The mites died soon afterwards and turned brownish in color. They attributed this mortality and change in color to a fungus disease. Re-examination of slides of diseased mites made by Mason in 1922 showed that the mites had a fungus disease now known as Hirsutella thompsonii Fisher. This disease of citrus rust mites was described by Fisher (1950). Swirski (1958) reported offcolor citrus rust mites in Israel and that they were pale yellow but turned light brown, and then brown, as they become older. His data showed that this color change was normal and must be differentiated from a change in color as a result of disease. Swirski stated that occasionally young adults and even larvae, turn brown, but this generally occurs when there is a disease evidently caused by fungi. A laboratory colony of citrus rust mites was established on Murcott honey orange seedlings early in 1961. The mites were kept in a ventilated greenhouse until May, 1961, and, subsequently, in air-conditioned greenhouses at 75-850 F. Additional mites were added to the colony in June, 1961. The mites in this colony came from a calamondin and a variegated lemon tree at the Horticulture Field Station in Orlando. During the summer and fall of 1961 numerous offcolor mites were observed in the colony of citrus rust mites. Offcolor citrus rust mites found during August were examined and found to have the fungus disease, H. thompsonii. Additional offcolor mites found in the colony and during