The hawthorn spider mite (Tetranychus viennensis Zacher) and two-spotted spider mite (Tetranychus urticae Koch) accepted all 13 apple cultivars given to them. The hawthorn spider mite most rapidly began permanent feeding on the apple cultivars: Priam, Witos, Pionier and Freedom. The two-spotted spider mite behaved similarly, but on the cultivars Romus, Primula, Florina and Lodel. The time of permanent feeding for the both spider mile species varied much, ranging from 1 min 8 sec to 21 min and 42 sec.
Females of the hawthorn spider mite (Tetranychus viennensis Zacher) showed the highest fecundity on the apple cvs. Novamac (29.0 eggs) and Freedom (28.0 eggs), whereas the least number of eggs laid out by tchem was found on the cvs. Primula (18.6 eggs), Lodel (22.5 eggs) and Pionier (25.7 eggs). Females of the two-spotted spider mite (Tetranychus urticae Koch) oviposited the largest egg numbers on the cvs. Novamac (22.0 eggs) followed by Freedom (22.2 eggs), while the lowest egg numbers were oviposited on the cvs. Lodel (10.7 eggs), followed by Primula (13.8), Pionier and VI-17 D₂ (16.5 eggs). Morphologico-anatomical structure of apple leaves and particularly the thickness of lower epidermis, spongy and palisade parenchyma significantly influenced female fecundity of the both, hawthorn spider mite and twospotted spider mite. Lower epidermis was the thinnest in the apple cvs. Priam (10.3 nm) and Freedom (12.5 nm). Spongy parenchyma was the thickest in the cvs. Romus (113.5 nm), Redfree (107.6 nm) and Freedom (104.7). Palisade parenchyma was the thickest in the cv. Romus (129.3 nm), Jonafree (122.9), Freedom (119.2) and Witos (118.3).