Public Health Service Investigation Commission to the China-Burma highway, Chefang (vicinity), China. Small irrigation ditch in the rice fields formerly had anopheles minimus mosquitoes breeding in pockets all along it. It has been rechanneled, as indicated by the new mud piled up on both sides. But the cattle have already trampled it; vegetation is growing in the cattle tracks and minimus are starting to breed in it again. The ditch had to be dusted with Paris green