The scaling of body proportions in I. graellsii is analyzed as body mass in dried specimens and linear dimensions are measured from photographic slides. Results indicate that abdomen mass shows positive allometry with body mass in both sexes, and thorax mass also does so in males. Wing area increases with body mass as expected from geometric similarity, but head width shows negative allometry with body length in both sexes. All traits excepting wing area are sexually dimorphic, but no difference was found in body proportions between female phenotypes of this species. Results indicate that larger individuals allocate more energy to reproduction. This is discussed in relation to the constraints imposed by the energetics of flight in larger individuals.