In recent years, the small brown planthopper, Laodephax striatellus Fallen, became more Important in northern Vietnam. By using sweep - netting to collect Insects In the field, the first time it was demonstrated that the small brown planthopper occur during the winter in northern Vietnam. Small brown planthopper occurred on ratoonlng and rice seedlings at low density, sampling in 0.2 to 1.5 adults per 30 sweeps. Experimentally In the greenhouse was determined that the life - cycle of small brown planthopper depends on the temperature. The life - cycle of small brown planthopper was 31.67, 25.44 and 21.86 days at 23.06°C, 31.51°C and 29.69°C, respectively. On average temperature at 23.06°C was more advantageous for development of the small brown planthopper than 29.69°C and 31.51°C.