134 ERNEST HILL AND L. G. HAYDON. 



Antenna. — No branched hair on shaft, terminal spines 

 equal, hair divides into four. 



Frontal hairs. — Three pairs. Anterior median straight 

 with fine spicular branches, often difficult to discern in living 

 larvte ; antero-external and posterior small, fine, and in 

 instances bifurcate; subject to variation (vide PI. XVI, 

 fig. a). 



Palmate hairs. — Relative to larva very small ; average 

 radius, 0*094 mm. ; entirely absent from thorax, rvidimeiitary 

 on first abdominal segment (PL XVI, fig. c) well developed 

 on second to seventh (PI. XVI, fig. h; PI. XXIV, fig. 6). 

 Relation of length of filament to length of leaflet, together 

 with filament, averages as 0'34 to 1 ; maximum, 0"37, 

 minimum, 0*29. 



The combination of frontal and palmate hairs is quite 

 distinctive. 



Habitat. — Preferential situation rather dirty water, by 

 reason of which this larva, much more thau any other 

 Natal species, is found covered with vorticella3. It is found 

 in rain-water pools, cattle foot-prints by streams and marshes, 

 roadside puddles, especially where refreshed by a slight flow 

 from a temporary spring, and residual pools in rocky streams, 

 (but only very occasionally in the actual watercourse), drains 

 and trenches in fields and marshy areas. 



Season. — Summer, from October to May. The summer 

 months hapj)en to be the rainy season, and it may be the lack 

 of suitable water which limits the breeding. It is notice- 

 able, however, that, in general, the water in which it is 

 found is quite bare of shade, and commonly quite warm to 

 the hand. 



Relation to Malaria. — Found throughout parts where 

 malarial fever is epidemic, but not encountered where the 

 disease is absent or sporadic ; the appearance of larvae pre- 

 cedes the rise in malaria incidence, Avhich commences sharply 

 about five or six weeks later, and sinks to minimum a few 

 weeks after larvae cease to be found. Almost all the imagines 

 captured by us in infected habitations in 1905 were of this 



