Understanding the prey preference of polyphagous predators is important to enhance their benefits as biocontrol agents. Two predators, Macrolophus basicornis (Stål) and Engytatus varians (Distant) (both Hemiptera: Miridae), attacking eggs of the two lepidopteran pests Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) and Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae) were assessed under laboratory conditions. During 24 h predation rates of the two mirids were measured and their prey preference was quantified using Manly’s preference index. Behavioural patterns of each predator were observed during one hour and the following components were separated: moving, searching, resting, prey encountering, preying, feeding on leaflets and cleaning. Subsequently, encounter-, acceptance-, and predation rates were calculated. According to Manly’s preference index, E. varians had a strong preference for N. elegantalis when offered together with T. absoluta, while such a preference was not evident for M. basicornis. Compared to E. varians on T. absoluta M. basicornis spent more time searching for both prey and needed less time to encounter fresh eggs. Due to its higher attack rate, M. basicornis displayed a higher predatory efficiency on both pests. Both mirids spent longer time prey searching, resting and feeding (including sucking of leaflets) than on the remaining activities. Engytatus varians, however, spent more time feeding on plant tissue than M. basicornis. These results demonstrate the performance of both mirids as biocontrol agents against T. absoluta and N. elegantalis. Based on our results, we conclude that both mirids could be considered in pest management strategies in tomato crops.