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Observations were made on the feeding behavior of the two main phytoseiid species in Spanish Citrus orchards, Euseius stipulatus (Athias-Henriot) and Typhlodromus phialatus Athias-Henriot. The experiences were carried out by rearing the predatory mites on excised orange leaves, and always with an excess of the prey the Citrus Red Mite (= CRM) Panonychus citri (McGregor). In experiments with all stages of CRM, the number of prey killed per hour was 5.12 and 2.00, the percentage of successful attacks, 58 % and 21%, and the mean time spent feeding on each prey was 5.1 and 12.2 minutes for starving females of E. stipulatus and T. phialatus respectively. E. stipulatus feeds on all stages of the prey except eggs, and T. phialatus, on all stages, except males. Both species attack much less successfully females of P. citri rather than immatures. In experiments with adult females and eggs of P. citri as prey, the mean number of prey killed daily was 4.51 females for E. stipulatus, and 2.01 females and 2.12eggs for T. phialatus. Considering this killing rate and the number of eggs laid by the predators in the same period, it can be concluded that E. stipulatus consumes only 30 % of the content of the preys killed, whereas T.phialatus consumes a percentage of prey variable between individuals and ranging from 40 % to I00 %. These differences in feeding behavior between the two species could partly explain differences in their efficiency as biocontrol agents of P. citri observed in the field.

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