Consumption rates and utilization efficiencies of four species of polyphagous Lepidoptera feeding on sycamore leaves

Four species of Geometridae showed similar consumption rates and approximate digestibilities (100 x ingestion-egestion/ingestion) of sycamore leaves (Acer pseudoplatanus L.). A significant decline in E.C.I. (100 x growth/ingestion) and E.C.D. (100x growth/ingestion-egestion) with increasing larval weight is reported. The earlier descent from the sycamore canopy ofErannis defoliaria Cl. andOperophtera brumata L. larvae, to pupate in the soil, in comparison withAlsophila aescularia D. and S. andAgriopis aurantiaria Hb. larvae is discussed in relation to small differences in the utilization efficiencies of final instar larvae. Later descending species suffered greater predation by wood-ants in the field site studied.