. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 65 (iuenth\ the period>s during- which greatest injiiiT is done. Deter- minations of this character were made in connection with the previ- ously mentioned ])reeding work. Measurements made of the length of the bod}^ are of but little use, since the}^ ma}^ be varied so much b}- the movements of the larva. There is a rather constant and gradual increase, however, from birth to maturit3^ as shown by the measurements given below, which are averages of twent3"-tive larvae. Table XX.âShowing amount of gr
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 65 (iuenth\ the period>s during- which greatest injiiiT is done. Deter- minations of this character were made in connection with the previ- ously mentioned ])reeding work. Measurements made of the length of the bod}^ are of but little use, since the}^ ma}^ be varied so much b}- the movements of the larva. There is a rather constant and gradual increase, however, from birth to maturit3^ as shown by the measurements given below, which are averages of twent3"-tive larvae. Table XX.âShowing amount of growth during, amJ lengtli at end of, each instar. Instar. Amount of growth during each in- star. Length at end of each in- star. I II Ill IV V VI mm. \ mm. t 1 4. 53 ! ⢠' Thus it will be noticed that a larva shows a greater amount of growth during each succeeding larval instar. This is shoA^n graphically in the accompanving curve (fig. 6). More accurate measurements are those based upon the size of the head, which does not change between the molts, and thus serves b}^ its almost constant size to identify the instar of any given larva. By meas- uring large numbers of head casts thrown off at the molts, it was found that they are fairh^ constant for each instar, sufficiently so to enable one to tell the stage of any larva positiveh\ The following table is compiled from measurements of over one hundred specimens:. I II III IV V VI Fig. 6.âDiagrammatic represen- tation of comparative rate of growth of larvae during dif- ferent instars (original;. Table XXI.âShowing average width of head casts for respective larval instars. Width and range. Stagel. Stage II. Stage III. Stage IV. Stage V. Stage VI. Width mm. («) mm. â mm. 0. 67-1. 00 mm. mjii. 1. 73-2. 28 mm. 3 95 Kange 2 85-5 00 a Practically Please note that these images are extracted from scanned page imag
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