The efficiency of defensive mechanisms in 11 European aposematic species of Heteroptera against various passerine predators was analysed. Bird species differed in their reactions to aposematic preys: small insectivorous birds generally avoided aposematic bugs, but granivorous birds as well as large insectivorous birds frequently attacked them. The ability to overcome heteropteran chemical defences appears to be connected with the larger body size of birds and with their food-storing behaviour. From the bird’s point of view, various red-and-black aposematic species of Heteroptera form a mimetic complex. However, antipredatory defence properties of individual species differ substantially in their efficiency against bird predators, and the nature of the mimetic complex is rather quasi-Batesian than Müllerian.