NUMBER OF INSTARS OF THE PITCH PINE TIP MOTH, RHYACIONIA RIGIDANA (LEPIDOPTERA: TORTRICIDAE, OLETHREUTINAE)
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AbstractHead capsule widths were measured on 962 larvae of Rhyacionia rigidana (Fernald). Five instars were detected using multimodal analysis, and normal distributions of head widths for each instar are given. Regression using an exponential growth model was used to generate mean head widths according to Dyar's rule. These widths did not differ significantly from observed widths.