POLYPHAGY AND ADULT BODY-SIZE IN GEOMETRID MOTHS

We compared the average body size (wing span) of Finnish geometrid mot h species in relation to their degree of polyphagy and quality of food . The first hypothesis, originally constructed for mammals and birds, states that smaller species should more often be specialists than larg e species, because of the different relationships between body size an d home range size, and body size and daily energy requirements. Accord ing to the second hypothesis, smaller species should feed more often o n herbs than do larger species, because of the different defence mecha nisms of herbs and woody plants. The results support both of these hyp otheses. Specialist species are smaller than oligophagous or polyphago us species, and small species concentrate on herbs. We conclude that q uality and quantity of food resources may explain the pattern.