author(s)
Anjali MS, G Sridevi, M Prabhakar, M Kalpana and B Pushpavathi

abstract
Sorghum is attacked by many insect-pests which are the principal limiting factor for its productivity throughout the country. Corn leaf aphid, Rhopalosiphum maidis is widely distributed and one of important pest on sorghum. The study of biology is important for understanding the form and extent of its population growth. R. maidis on sorghum had a life cycle of 7.79±0.12 days, adult longevity of 12.27±0.27 days, life span of 16.25±0.80 days, fecundity and rate of reproduction 35.97 progenies/female, 9.15 progenies/female/day at 27 ±0.5⁰C. Life table parameters includes net reproduction rate (R₀) 45.05, mean generation time (T_c) 9.24, intrinsic rate of natural increase (r_m) 0.44, innate capacity of increase (r_c) 0.41 and corrected mean generation time (T) 8.73 days, respectively. Nymphs developed through four instars and transformed into adults. The length and width of different nymphal stages of R. maidis were: 720.57± 9.95 µm and 303.62 ± 5.59 µm (1^st instar); 978.46 ± 13.51 µm and 412.83 ± 5.53 µm (2^nd instar); 1399.52 ± 24.56 µm and 581.74 ± 12.33 µm (3^rd instar); 1737.5 ± 20.28 µm and 733.98 ± 10.96 µm (4^th instar), respectively. The adult were yellowish green to dark olive green or bluish green and measured 1833.63±15.89 μm in length and 783.26±10.82 μm in width.