Population differences of Texas citrus mites on leaves of four orange varieties in Texas.

Eutetranychus banksi (McGregor), was more numerous on ‘Marrs’ than on ‘Pineapple’ or ‘Valencia’ orange leaves in 5 of 9 years and more numerous than on ‘Hamlin’ orange leaves in 4 of 9 years (1971–79). The 9-year analysis showed Marrs to have more mites than the other varieties and Hamlin to have more than Pineapple and Valencia. Double oil treatment plots had fewer mites and eggs than non-oil and other oil treatment plots in the 9-year analysis. During the 9 years, egg numbers were only 4% greater than mite numbers. Yearly peak populations usually occurred during the May–September period. However, the peak populations occurred in mid-March of 1974 and 1976 and were related to the larger winter carry-over numbers and more hours at and above 21.2°C prior to the peak.