Objective To study the biological characteristics of fruit fly, Rhagoletis batava obseuriosa Kol. (RBO) (Diptera: Tephritidae).

Method The life cycle and biological characteristics of RBO, including eclosion, mating, oviposition, pupation and population dynamics were studied through laboratory and field observation in Dengkou county, Inner Mongolia.

Result Adult RBO occurred from the middle June to the early August, and weather could have impact on adult amount. About 81.3% of RBO emerged from 6:00 to 10:00, and the peak time was 8:00 to 9:00. The larvae came out of fruit and pupated mainly in the early morning from 0:00 to 6:00, especially from 3:00 to 6:00. The mating time mainly occurred in the daytime and there were two peaks from 12:00 to 13:00 and 16:00 to 17:00. Usually, the mating lasts 239 ± 11.86 min. The fruit fly preferred to lay one egg into one fruit which the length was 6.65 ± 0.28 mm and the width was 5.47 ± 0.40 mm. The mating and egg-laying behavior of R. batava obseuriosa were studied in details too.

Conclusion There is only one generation of RBO per year in Dengkou county, Inner Mongolia. The larvae develop within the fruit of Hippophae rhamnoides and pupate in the soil. Though adult period was short, it should be an exact stage for controlling the pest.