This thesis was developed in order to determine whether the selected species most commonly kept feeding insects affect fertility in captive bred assassin bugs \kur{Platymeris biguttatus}. Used feeding insects were \kur{Blaptica dubia} roaches, \kur{Acheta domestica} crickets and larvae of \kur{Tenebrio molitor} bugs. The reason of using assassin bugs \kur{Platymeris biguttatus} was their popularity among breeders, their easy care needs and their superior fertility. Assassin bugs were kept in an air conditioned room with a constant temperature conditions and light regime. It has been shown that the given diet has no effect on fertility in this kind of bugs, also that breeding in groups has negative impact on fertility of this assassin bugs species. The results of this study could demonstrate the importance of proper feeding in keeping these bugs and help breeders to have better results.