Collecting the shortest-term rice varieties which have the growth and development period under 100 days and gain over 50 quintal/ha, to cultivate the earliest crop of Thanh Hoa Province is an imperative issue that the producing reality requests. The earliest crop is often harmed by pests in reducing the productivity and quality. In collected varieties to be cultivated in the earliest crop, it is seen that the development of pests is also different depending on the rice varieties. To Khang Dan 18, Gia Loc 102 rice varieties, their density of pests appears higher than Hong Duc 9 and TH3-5 rice varieties. Therefore, farmers should use Hong Duc 9 and TH3-5 rice varieties in the earliest crop production due to their stable productivity and their lower damage caused by pests to ensure the high productivity and quality of rice.