341] LARVAE OF THE TENTHREDINOIDEA—YUASA 23 



caudal end with the epimeron and coxa. This is the lateral cervical sclerite 

 (les), which is always present and usually distinctly colored — brownish or 

 blackish. The cervacoria is continuous with the submentum on the 

 ventral aspect, and is often produced on the meson as a small mound-like 

 setiferous protuberance, as in Strongylogaster. 



Thorax. — The prothorax is usually constricted on the cephalic portion, 

 the dorsal aspect is declivous, and the lateral aspect is produced. The 

 dorsum is typically divided into a narrow cephalic portion and a wide 

 caudal one, which in turn may be subdivided into two or more annulets 

 (Fig. 65). The first division is usually setiferous on the lateral aspect, 

 while the second division is setiferous on the dorsal aspect. On the middle 

 of the lateral aspect there is a large spiracle. This is the mesospiracle 

 (msp), which has migrated onto the prothorax. There is another setiferous 

 area cephalo-ventrad of the spiracle. The prothoracic leg is attached to 

 the latero-ventral margin of the segment, ventrad of the setiferous sub- 

 spiracular area, which is usually produced as a lobe and which Crampton 

 (1918) has designated as the surcoxal plate. There is a small, usually 

 strongly chitinized sclerite cephalad of the leg. This is the episternum- 

 epimeron, or the eupleuron of Crampton. The dorsal aspect of the pro- 

 thorax and often the lateral one may be chitinized and colored, forming 

 shield-like areas as in the Xyelidae and certain leaf-miners. The proster- 

 num is usually membranous, subdivided into two or more annulets, but 

 sometimes it is flattened and strongly chitinized as in Metallus. There is 

 usually a small pit or chitinized rod near the caudal part of the segment on 

 the ventral aspect. This is the profurcellina (Pfn) and marks the caudal 

 limit of the prosternum. The meso thorax and metathorax are more 

 or less similar in structure, frequently the largest segments in the body, 

 more or less ring-like and often distinctly annulate. The metaspiracles 

 (tsp) are located in the metacoria and are usually minute and functionless. 

 The mesothorax and metathorax resemble the prothorax in other details. 

 In the Fenusinae (Fig. 21) and Metallus (Fig. 22) the dorsum of the 

 mesothorax and metathorax is provided with an ovoid, fleshy, sucker-like, 

 low protuberance (scp) on each side of the meson. Its function is not 

 known. Dimorphopteryx is characterized by the presence of a pair of 

 prominent dorsal protuberances on the prothorax and a median protu- 

 berance on the mesothorax. 



Thoracic Legs. — The larvae of the Tenthredinoidea, with the exception 

 of the Oryssidae, possess three pairs of thoracic legs. They are the most 

 persistent of all the thoracic and abdominal appendages and as a rule are 

 very similar in structure, both facts indicating a common origin. A typical 

 leg consists of five more or less well-chitinized segments: coxa, trochanter, 

 femur, tibia, and a distal segment representing the fused tarsus and tarsal 

 claw. 



