O rnam ental plants have been densely used in botlı internal and external places. C rataegus m on o g yn a is one of these ornam ental plants that adds liveliness to these places. Three different Lepidoptera species nam ely A poria crataegi, E riogaster lanestris, Sa tu rn ia p a vo n ia belonging to different fam ilies that cause dam age on this plant have been investigated and som e m orphological and biological researches have been conducted. The observations have been com pared \vith those found in published.