REPRODUCTIVE CAPACITY OF THE HORSE CHESTNUT SCALE INSECT, PULVINARIA-REGALIS CANARD (HOM, COCCIDAE)

The surface area of pre-oviposition female scale insects was closely c orrelated with their dry and wet weight biomass, and was used as a con venient, indirect method of adult size assessment. Adult females at ov iposition were on average bigger when in low density populations than those in high densities, an indication of intraspecific competition in the nymphal stage. Larger females were found to be more fecund (laid more eggs), and produced larger eggs, than smaller females. No signifi cant differences were detected between fecundities of females which ha d fed as nymphs on different species of host tree, and the general adu lt size/fecundity relationship was of sigmoid form, indicative of a ma ximum reproductive potential, which was independent of host tree speci es. Comparisons with other Hemipteran species indicated the generalist nature of P. regalis, adapted to widespread dispersal and large first instar losses from populations.