1914 ENTOMOLOGICAL SOCIETY. 71 



area is also distinct in the Tenthredinidae (Figs. 6-8 and 12, sa). There is 

 also an area that is marked in certain larvae, which is located above the spiracular 

 area and behind the spiracle and appears to be formed from the fourth and sixth 

 annulets. This has been designated the postspiracular area (Figs. 6-8, 12 and 

 27, pa). There is a third area, which is located between the base of the proleg and 

 the spiracular area, the pedal area (p). This area varies considerably, even in the 

 same insect; on some segments it may be a single area and on others divided into 

 two (Fig. 27, p). 



The body, comprising the thorax and the abdomen, may be either black, white, 

 green, spotted or banded. The great majority of the larvaj are white or green. In 

 the green larvae the color is due in great part to the blood or the food contained in 

 the alimentary canal. In such larvae the dorsal vessel or heart also usually shows 

 as a darker median band. The air tubes or tracheae along the lateral margins of the 

 dorsal vessel and along the lateral aspect of the body and connecting the spiracles, 

 show as silvery or frosted lines, either one or both of these may be obscured. In 

 a few species there is a double row of dorsal yellow spots in certain Nematinae and 

 a lateral row of similar spots on the postspiracular area of certain segments. 

 These yellow spots are due to the presence of patches of yellow adipose tissue or 

 fat, which can be seen through the transparent cuticle. Markings due to the food, 

 the colour of the blood, the air-tubes, or the adipose tissue are serviceable in separ- 

 ating different species, but unfortunately they disappear wholly or in part when 

 the larvae are preserved in alcohol. Frequently, however, an entirely new set of 

 colour characters appear, due to the preservative fluid. 



Many species of larvas are marked by bands or spots of varying degrees of 

 prominence, which are due to pigmented colours. The median dorsal black line 

 of Cimhex is such a color, a median black line is usual for the group and is charac- 

 teristic for the genus. When pigmented dorsal bands are present, they are usually 

 located one on each side of the dorsal vessel. There is also frequently a band on 

 each side along the line where the dorsal and lateral aspects meet. These line? are 

 continuous with the fuscous bands found on the vertical furrows. The bands, 

 while appearing continuous to the unaided eye, are seen, when examined with a 

 lens', to be a series of spots interrupted by the crossing of the furrows between the 

 annulets. There are frequently interrupted bands on the pleural aspect formed 

 by a series of spots on the spiracular and pedal areas (Fig. 27). 



The thoracic and abdominal segments of most of the larvae examined bear 

 setffi (Figs. 6-8, 12, and 27). The arrangement of these setae, as groups of setae, 

 not as individual setae, is characteristic for genera at least. In the Emphytin^, cer- 

 tain Selandriinas, and Tenthredininge, the setae are fine and of the same colour as the 

 body cuticle (Fig. 12), consequently inconspicuous and readily overlooked. They 

 are arranged in transverse bands and are usually placed on the first and third 

 annulets or the first, third, and sixth annulets. There are also longitudinal bands 

 on the spiracular and pedal areas. In many Blennocampinae (Fig. 8) the setae 

 are large and spine-like, bifurcate at apex. In some species of this subfamily the 

 terminal bifurcate portion is wanting and they are represented by white protuber- 

 ances or black spots. These larvae during their ultimate stage, even the spiny 

 species, have apparently naked bodies. The bifurcate spines are replaced by fine 

 colourless setse like those of the Emphytim^. A different condition is found in 

 certain ISTematinae and the Acordulecerinae, where the setae are fine and colourless 

 and difficult to locate in all the stages but the ultimate, where each seta is placed 

 on a small black or fuscous spot, completely changing the appearance of the larva 

 and distinctly marking the location of the setae. 



