Studies on filariasis. III.Dirofilaria immitis: emergence of infective larvae from the mouthparts ofAedes aegypti

Abstract Infective larvae of Dirofilaria immitis commonly escaped from the tips of the Iabella and rarely from the mid-portion of the labium of Aedes aegypti as they engorged blood or just probed on mice. During the infective feed a small quantity of liquid, not more than 1 µI in volume, accumulated around the emerging larvae. Liquid was never seen when uninfected mosquitoes engorged on mice. This fluid is of insect origin and probably haemolymph that exuded from the lumina of the labella or labium during worm emergence. The presence of the fluid prevents dessication of larvae on the surface of the skin and maintains them in a liquid medium until they enter the puncture wound that remains after withdrawal of the biting fascicle. The possible effects of the fluid on the geographical distribution of mosquito borne filariae are discussed.