94. MOSQUITOES OF NORTH AMERICA 
differ greatly according to the genera and species and these differences are 
brought out in the systematic part of this work. 
The lateral comb of the eighth segment shows great variation, not only in the 
shape of the scales, but their number and arrangement. The scales may even be 
absent altogether, as in Joblotia, where they are represented by single spinose 
tubercles, or in Megarhinus by a chitinous plate. In other cases, as Uranotenia 
and Anopheles, there is a plate with a series of teeth along the margin. The 
jarve of Bancroftia are remarkable in that both comb-scales and plates are 
present, and in the last stage chitinous dorsal plates are also present on the sixth 
and seventh segments. 
On the ninth segment the chitinous plate differs greatly in shape and size in 
the last stage larva of different species. It may completely encircle the segment 
or be reduced to a dorsal saddle. In some forms there is a group or row of spines 
or scales, laterally along the hind margin; in Megarhinus these form an elabo- 
rate fringe. Laterally, on each side, is usually inserted a small hair or hair-tuft, 
occasionally this becomes conspicuous. The ventral brush also varies much in 
development ; in some cases it is continued into the chitinous plate, in others it 
is much condensed. In some cases the ventral brush is inserted upon a separate 
chitinous plate which is perforated for the insertions of the hair-tufts. In the 
Sabethini there is no ventral brush but only a pair of lateral tufts or hairs below 
the margin of the dorsal plate. 
The tracheal gills show great modifications in adaptation to larval habits. In 
certain larve which do not come to the surface for air the tracheal gills are very 
large and are traversed by a large trachea. In other forms they are obsolete and 
only represented by fleshy papille. This is particularly true of the species in- 
habiting saline water. 
The larva of Sabethinus is remarkable in the presence of a pair of chitinous 
hooks upon the seventh segment, situated upon fleshy tubercles, dorsally, near 
the end of the segment. In some larve the entire integument is covered with 
minute hairs or spicules and this may also be true of the plate of the ninth seg- 
ment and sometimes of the breathing tube. 
In certain larve there are small chitinous plates at the insertions of the large 
hairs on the thorax and sides of the abdomen. These plates are particularly well 
developed in Megarhinus and Aédeomyia. In many larve there are stout spines 
at the angles of the thorax which prevent the long hairs from being bent back- 
wards. 
There is wide diversity in the coloration of mosquito larve. While certain 
forms have a characteristic coloring there is often great variation in this respect ; 
color, beyond the fact that certain genera show a characteristic coloring, can 
not be used for identification. 
All the larvee of the tribe Sabethini that we have seen have a characteristic 
pale appearance. The body is opaque creamy white and the head and other 
chitinous parts light yellow. Only the foramen of the head is more or less 
broadly edged with black, and sometimes the anal plate also shows a dark 
margin. The larve of Megarhinus are dark and the integument shows a more or 
