Examined British aphids, British moths, and Canadian Macrolepidoptera. Degree of polyphagy was negatively correlated or uncorrelated with population variability, ie highly polyphagous species have a weak tendency to be less variable than host specialists. This lends some support to the argument that polyphagous species may be less susceptible to fluctuating resource levels. Population variability in monophagous or oligophagous herbivorous insects may, in part, reflect variation in resource levels. -from Authors