On oranges, the predominant damage is russeting which frequently appears earlier in the season than on grapefruit, but has the same injury patterns. Mite feeding causes water loss from the fruit and the resulting concentration of sugars make fruit sweeter to the taste. Extreme infestations of rust mite cause fruit to appear dusty and lack luster. Citrus rust mite also frequent foliage, with the underside of leaves a favorite feeding place. Heavy infestations result in russeted or bronzed leaves, which may fall prematurely.
Extensive defoliation impairs general tree health and can cause reduced fruit yields.
The 2 immature nymphal stages are morphologically similar to the adult, but are smaller and paler yellow. In the summer, duration of each nymphal stage is only 2-3 days. The entire rust mite life cycle can be completed in 7-10 days in the summer, but may take 20 or more days in the winter. Numerous overlapping generations can occur during a single season. It is easily distinguished by a purplish-red body with long reddish bristles on numerous prominent tubercles.