343] LARVAE OF THE TENTHREDINOIDEA—YUASA 25 



nae (Fig. 140) also possess small four-segmented legs but, unlike the 

 Phyllotominae, have simple and ring-like segments and claws normal in 

 form. The Hylotominae differ from the other subfamilies in possessing 

 apparently six-segmented legs. Their distal portion consists of a distinctly 

 separated tarsus and claw and bears an empodium-like fleshy lobe on the 

 caudal portion of the claw. The minimum number of segments is found in 

 the legs of the Schizocerinae (Fig. 139), where the mesothoracic and 

 metathoracic legs consist of only three simple cylindrical segments, while 

 the prothoracic legs are composed of four. There is a well-developed 

 fleshy subglobose lobe caudad of the claw. It is interesting to note that 

 the gall-makers, for example, Pontania have essentially the same type of 

 legs as the leaf -feeding Nematinae (Fig. 133), while the leaf-mining larvae 

 of the Fenusinae, Schizocerinae, and others, have modified legs. The 

 highly specialized families, Cephidae, Xiphydriidae, and Siricidae, possess 

 fleshy, indistinctly segmented rudimentary legs which are never provided 

 with claws. The most specialized family, Oryssidae, is entirely apodous. 

 The legs present, therefore, very good characters for differentiating the 

 families and the subfamilies of the Tenthredinoidea. The phylogenetic 

 significance of the thoracic legs is quite evident. 



Abdomen. — The segments composing the abdomen, with the exception 

 of the two caudal segments, are more or less similar in structure, ring-like, 

 and usually subdivided into four to seven annulets. Segments 2-7 or 2-8 

 and 10 usually bear a pair of larvapods, the so-called "prolegs," on the 

 ventral aspect. The first and ninth abdominal segments never possess 

 larvapods except in the Xyelidae. The third abdominal segment is more 

 typical than the other segments and least modified, and for this reason 

 has been used as a type for description. In a typical larva this segment is 

 subdivided into a number of annulets on the dorsum and latus dorsad of 

 the spiracular line. The latus ventrad of the spiracular line is typically 

 lobe-like, setiferous, and distinguishable as two areas, the subspiracular 

 area {ssl) or the surpedal area {sdl) according to the location. When 

 these areas are distinctly lobe-like they are designated as subspiracular 

 lobe and surpedal lobe. The latter corresponds to the thoracic surcoxal 

 plate of Crampton. The subspiracular and surpedol lobes sometimes fuse 

 and extend the full length of the segment as an oblique fold, as in wood- 

 boring larvae and the Hylotominae. In the latter this lobe is conspicuously 

 produced laterad, making the segment distinctly flattened. The sub- 

 spiracular and surpedal lobes, when fused, are known as the sublaterai 

 lobe {sll). The larvapods are located on the ventral aspect some distance 

 from the meson. The sternum is divided into two or more annulets, the 

 annulation being usually distinct but its exact limits diflScult to determine 

 on account of the presence of the larvapods. The intersegmental coria 

 {cor) is distinctly indicated on the venter (Fig. 81). The segmentation 



