Ti, THE REPOKT OF THE No. 36 



In certain Nematinse (Fig. 27) and the Hylotominfe (Fig. 7), the setae are 

 arranged in groups or singly on small elevated areas. The larvae of Pteronus 

 ribesii and of Hylotoma show the maximum type of the development of this form 

 of maculation, where the spots bearing the setae are arranged in transverse bands 

 on the dorsal and lateral aspects of the annulets and in longitudinal spots on the 

 areas adjacent to the spiracles. The number and size of- these spots, which are 

 black, give the larva a predominance of this colour. These black areas are constant 

 in their location for a given annulet for successive segments for a given larva. 

 . This has been assumed by some writers to be the generalized type of maculation, 

 but an examination of a series of species will show that it is an extreme type of 

 specialization. In some nematids similar spots are found only on the thoracic 

 segments, in others they may be limited to the dorsal aspect of the body or to the 

 lateral aspect. The larva of Croesus latitarsus, which apparently has a somewhat 

 similar type, is in reality entirely different. The individual spots in this species 

 extend on to two or more annulets without regard to the seta, while in Pteronus 

 ribesii (Fig. 27) the setae are all located on the spots, but in Hylotoma (Fig. 7) 

 there is an abundance of setae between the spots. 



There is still another type of colouration, which is characteristic of a large 

 number of larvEe of the Emphytinae and Selandriinae. These larvae during the 

 first two or three instars are opaque white in colour. The lateral aspects of the 

 body in the region of the spiracles, as they age, becomes gradually infuscated. 

 The venter, including the prolegs and a narrow band along the ventral margin of 

 the lateral aspect, remains opaque white. This lateral infus'cated band is only 

 slightly indicated in the first stages of its appearance and in some species never 

 gets any stronger throughout the life of the larva. But among other species all 

 degrees of intensity occur, from a light brown to a chocolate brown and black. 

 The median part of the dorsum is white in the infuscated species, but with the 

 increase in intensity of the lateral bands, the dark colour suffuses over the entire 

 dorsum and in the very dark species the pleura and dorsum are a uniform dark 

 chocolate colour during the last instar. The larvae which develop this type of 

 colouration usually rest curled up on the underside of the leaf like a snail shell or 

 helix. In the very dark coloured forms the white of the ventral surface is com- 

 pletely obscured, and the anal prolegs, which are white, are turned so as to be ' 

 exposed and to form the apex of the helix and look like a white eye. Each seta is 

 placed on a minute white spot ; with the dark background they stand out distinctly. 



The larvEe of certain Tenthredininae have a similar type of colouration, but 

 they differ from the Emphytinfe and Selandriinae in that they have an ultimate 

 stage. No matter what the colour during the preceding instars, they are immacu- 

 lately glassy-green during the ultimate stage. 



The Cladiinae feed stretched out flat on the surface of the leaf. The adults 

 have generally been assumed to be closely allied to the Nematinae and usually 

 associated with them. x\ll the larva; of this group that have been examined are 

 entirely different in appearance from the nematids. They practically all have the 

 same type of colouration described above for the emphytids and selandrids and 

 during their last instars are highly coloured. Their resemblance to the Emphytinae 

 is enhanced by their flat body and method of feeding. They are also peculiar in 

 having a great abundance of long seise on the head as well as on the body segments. 



In Cimhex and Trichiosoma the body is green or white, a median dorsal black 

 line in Cimhex. The pleural part of the annulets and the areas adjacent to the 

 spiracles hear a number of papilla-like elevations (Fig. 6), which are more prom- 



