Growth and its variation of the Kurashiki race of the Gypsy moth, Lymantria dispar L. : Problems on the breeding of insects for biological assay of insecticides XLVII

Under a laboratory condition of 16∿22℃ and of 40∿85% R. H., the larvae of the Gypsy moth, Lymantria dispar L., collected in Kurashiki, Okayama Prefecture were reared on leaves of the persimon, Diospyros Kaki L., individually with distinction of egg cluster. The females moulted five or six times in the larval stage and the males moulted four or five times. There was a tendency that the number of individuals having the less number of moultings is more than that having more number of moultings in both female and male. The relations between logwidth of head capsule and instar number were found to be represented by the 2nd or 3rd order regression equation. The variation of width of head capsules within the female or male individuals having the same number of moultings was significant even within the same egg cluster. In both female and male, larval development time of individuals having less number of moultings was shorter than that having more number of moultings. In the individuals having the same number of moultings, larval development time of female was longer than that of male. Pupal duration of female was shorter than that of male. Any significant difference in pupal duration was not recognized between the number of moultings. Total development times of larva and pupa of individuals having the same number of moulting were not different between female and male. Slight differences of total development time of larva and pupa were recognized among egg clusters. The relations of log cube root of cummulative weight of faecal pellets to instar number could be represented by the 2nd order regression equation. The weight of female pupae was much larger than that of male pupae and the weight of pupae having more number of moultings in their larval stage is larger than that of less number of moultings. The big difference of the length of fore wings was found between female and male but that differences could not be recognized am ong egg clusters, or between number of moultings.