The population ecology of Pardia tripunctana and Notocelia roborana, a bud- and a leaf-feeding tortricid respectively, on Rosa spp. was studied. Mortality factors of the egg and larval stages are low and density-independent. Pupal mortality in the soil is a regulatory mechanism: it compensates for density fluctuations, as independent of the initial pupal densities the densities of emerging adults are fairly constant. These mechanisms lead to low density levels, low resource utilization rates, and low density fluctuations. A steady state model is developed to describe the population dynamics. Both species therefore can be considered as “equilibrium species”.