Filariasis and Mosquitoes 
181 
It was formerly supposed that when the infested mosquito punc¬ 
tured the skin of man, the mature larvae were injected into the cir¬ 
culation. The manner in which this occurred was not obvious, for 
when the insect feeds it inserts only the stylets, the labium itself 
remaining on the surface of the skin. Fiillebom has cleared up the 
question by showing that at this time the filariae escape and, like 
the hookworm, actively bore into the skin of their new host. 
Once entered, they migrate to the lymphatics and there quickly 
become sexually mature. The full grown females measure 85-90 mm. 
in length by .24-28 mm. in diameter, while the males are less than 
120. Filaria in the muscles and labium of Culex. After Blanchard. 
half this size, being about 40 mm. by .1 mm. Fecundation occurs 
and the females will be found filled with eggs in various stages of 
development, for they are normally viviparous. 
Filaria philippinensis is reported by Ashbum and Craig (1907) as 
a common blood filaria in the Philippine Islands. As they describe 
it, it differs from Filaria bancrofti primarily in that it does not exhibit 
periodicity. Its development has been found to occur in Cidex 
quinquejasciatus , where it undergoes metamorphosis in about fourteen 
or fifteen days. There is doubt as to the species being distinct from 
bancrofti. 
Several other species occur in man and are thought to be trans¬ 
ferred by various insects, among which have been mentioned Taba- 
nidse and tsetse-flies, but there is no experimental proof in support 
of such conjectures. 
