34 
A Monograph of Culicidae. 
It will thus be seen that Anopheles larvae differ, and can be 
told from Culex by the relatively smaller head, the absence of 
any respiratory siphon, and the numerous paddle-like plumose 
bristles at the sides of the thorax and the first few abdominal 
segments. The latter structures act as balancers to keep the 
larvae level in the water when at rest. Other species are described 
further on. The bristles and hairs vary in number and form in 
the different species. 
Corethra larvae (Fig. 18).—Of Corethra we have had many 
detailed descriptions. The larvae are noted for their crystalline 
appearance when young, and are even semi-transparent when 
mature; hence their popular name of “Phantom larvae.” In 
some respects they resemble the “ Blood Worms,” or larval stage 
of the Cliironomidae. The head is small, much more so than in 
any of the preceding genera, and is narrower than any other 
part of the body except the two last abdominal segments, 
elongated with parallel sides, the front part being contracted so 
much so that it is little more than half the width of the hind 
part; on each side, in a depression, arise fine bristles more or 
less curved, and just behind these, a knife-like plate dentated at 
its free extremity ; the eyes are large, round and facetted,* and 
there is a smaller ocellus lying behind each large eye; the 
antennae are prehensile and are situated in front of the head, 
the basal joint bears five long somewhat bent bristles and also a 
sixth smaller bristle. The thorax is swollen, slightly more so 
behind than in front, laterally are a few small bristles cleft into 
rays at the ends; three on each side are distinct. The 
abdomen is composed of nine segments, which are longest 
behind ; the first segment is very small, the second a little larger, 
the others increase until the seventh ; the eighth is very small, 
and the ninth pointed ; each segment up to the seventh bears one 
or two pairs of bristles, many rayed at their ends ; on the venter 
of the ninth is a row of twenty-five long feathered bristles, which 
together form the “ swimming fan ” ; there are also four long anal 
bristles and also four anal papillae, long and slender and unarmed ; 
the anal hooks consist of two double oblique rows of hooks which 
surround the point of the anus like a wreath. There are four 
distinct respiratory sacs, situated as in Mochlonyx ; they contain 
no air, but are full of serum. There are no spiracles at all, and 
* When the larvae are first hatched the eyes are only small pigment 
spots (Miall). 
