335) LARVAE OF THE TENTHREDINOIDEA—YUASA 17 



granules showing thru the cuticle. The ocellarae are obsolete in the 

 highly specialized families, Xiphydriidae and its allies. The life-habits 

 are correlated with the presence and the degree of development of the 

 organs of sight. 



Front. — The area bordered by the epicranial arms on the cephalic aspect 

 of the head is the front (if). The ventral boundary is indicated by a 

 transverse depression connecting the ventral ends of the epicranial arms. 

 This depression is the fronto-clypeal suture (fcs). The depression is 

 usually concave dorsad and often obsolete at each lateral end. The 

 front is usually flattened or only slightly convex and bears scattered setae 

 which vary in number and arrangement in different genera and in arrange- 

 ment in different individuals. The extent of the front is determined by 

 the length of the epicranial arms. The front is usually subquadrate, 

 often wider than 1 ong, but in some cases, as in Caliroa (Fig. 53), it is 

 much longer than wide. In the absence of the epicranial stem the lateral 

 boundaries are indicated by the pretentorinae as in Tremex (Fig. 46). 

 Phlebatrophia (Fig. 37) is unique in possessing a distinct median longi- 

 tudinal furrow on the dorsal half of the front. 



Clypeus. — The area ventrad of the front is the clypeus (c). Its ventral 

 boundary is the clypeo-labral suture (els), and the lateral margins are free, 

 oblique, and converge ventrad. The clypeus is usually much wider than 

 long and is divided usually into postclypeus (po) and preclypeus (pe) by a 

 difference in color and by a transverse row of setae. Sometimes the 

 clypeal suture (cs) is distinct, as in some Nematinae (Fig. 31). The clypeal 

 setae vary in number from two to eight or ten but are constant within a 

 genus and often within a subfamily. Four is the most common number. 



Lahrum. — The small lobe attached to the ventral margin of the clypeus 

 is the labrum (/). It is usually transverse and has a median emargination 

 on the ventral margin. This emargination is usually shallow and broad 

 but occasionally very deep, as in Eriocampa and a few other Emphytinae. 

 Dolerus (Fig. 42) is characterized by the distinct asymmetrical median 

 emargination which makes the sinistral half of the labrum much smaller 

 than the dextral. The cephalic margin is nearly smooth and slightly 

 oblique in Tremex (Fig. 46). The labrum is very small in the Xiphydriidae 

 (Fig. 45). From two to several labral setae {Is) are borne on each side 

 of the meson, those near the meson being usually smaller than the lateral 

 ones. The number of labral setae are as a rule constant within a genus. 

 A row of setae which may be seen projecting from the ventral surface of the 

 labrum belongs to the epipharynx. The labrum is often divided into 

 halves by a distinct median longitudinal depression, as in Caliroa (Fig. 53), 

 Endelomyia (Fig. 48), and some Tenthredininae. This character is generic 

 in some subfamilies and only specific in others. The labrum in the Cim- 



