Problems on the breeding of insects for biological assay of insecticides

Abstract

Under the environmental condition of 25°C and 89% relative humidity, the larvae of the “Takatsuki” race of the gypsy moth, Lymantria dispar L., were reared separately on leaves of the zelkova-tree, Zelkova serrata Makino. The females of the “Takatsuki” race of the gypsy moth moulted six or seven times in their larval stage and the males moulted five or six times. In all of these cases mentioned above, the relations of log-width of exuviae of head capsule to instar number were found to be represented by two straight lines intersecting at a point between the 3rd and the 4th instars. We shall be able to determine the instar to which a larva belongs by measuring width of exuviae of the head capsule in the larvae ranging from the 1st to the 3rd instars, but we shall fail to tell the instar number by this method in the larvae ranging from the 4th to the last instars. © 1957, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.