| Summary: | On the basis of head capsule widths (HCWs) of field-collected and laboratory-reared larvae, the moth Gynaephora menyuanensis Yan & Chou (1997) (Lepidoptera: Lymantriidae) was first found to have six instars in the male and seven instars in the female. Mean HCWs were 0.68, 0.91, 1.22, 1.58, 2.06, 2.69, and 3.45 mm in field-collected larvae and 0.67, 0.87, 1.17, 1.54, 2.00, 2.59, and 3.24 mm in laboratory-reared larvae for first through seventh instars, respectively. Stadium duration, body length, and body mass of each instar also were examined. The first, second, third, fourth, fifth, sixth (♀, ♂), and seventh (♀) instars averaged 240.30, 15.32, 14.58, 14.74, 13.86, 15.90 (♂), 13.65 (♀) and 16.28 (♀) d in stadium duration; 3.95, 4.96, 6.07, 9.14, 13.31, 17.23, and 25.79 mm in body length; and 1.33, 3.46, 7.79, 17.32, 45.05, 103.07, and 217.24 mg in body mass under the field conditions. Analyses of the results showed highly significant exponential correlations of HCW with body length and body mass, and power function correlations of instar with HCW, body mass, and stadium duration, and S correlations of instars with stadium duration. A life cycle of G. menyuanensis required a year in the field, and the mean developmental time observed from egg to adult was ≈346 d in the male and 350 d in the female. Because abiotic and biotic environments of Tibetan-Qinghai Plateau are similar to Arctic tundra, with long severe winters and short cool summers, we compared HCW, body length, body mass, and stadium duration of G. menyuanensis with two congeneric species occurring in the Arctic, Gynaephora groenlandica (Wöcke) and Gynaephora rossii (Curtis) body mass.
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