Biological studies on the Hawaiian beet webworm, Hymenia recurvalis were carried out under laboratory conditions of 18.6 ± 2°C and 70 ± 5% R. H. The incubation period ranged between 5 and 7 days with a mean of 6.0 ± 0.3 days. The mean durations of larval, prepupal and pupal stages were 26.29 ± 0.3, 5.04 ± 0.08 and 16.86 ± 0.18 days, respectively. Mean adult longevities were 28.42 ± 1.80 and 26.08 ± 1.83 days, ranging between 19-41 and 15-37 days for female and male, respectively. The sex ratio was about 1 : 1.3 (♀ : ♂ ). Accumulative thermal units needed for certain biological features of H. recuurvalis were calculated and the estimated thermal thresholds were 10.97, 12.14, 10.49 and 13.55°C for egg, larval, pre – pupal and pupal stages, respectively. The corresponding values for the thermal units needed for development of these stages were 51.49, 168.47, 47.88 and 102.59 day degree at 25°C for the respective stages.