ABSTRACT
Anopheles dirus mosquitoes collected in the field of Khanh Phu commune, Khanh Vinh district, Khanh Hoa province were reared in the insectarium. The typical karyotype (2n=6) have 2 pairs of chromosomes and one pair of sex chromosomes. The chromosome III are the longest and submetacentric and the II are shorter and metacentric. The sex chromosome is heteromorphic. Three types of X (Xl; X2; X3) chromosomes and 2 types of Y (Yl; Y2) chromosomes were identified. The study on biological characteristics shows that An. dirus are anthropophilous has interest in human blood but they can feed on mice. Mosquitoes fed by human blood were found to lay more eggs (45 - 258 eggs) that those fed on white mice (15 - 148 eggs). The appropriate water level for the advanced development of larval stage should be 10mm to 20mm. Mass death of larvae was observed while protozoa intensively developed in the rearing aquarium.