ABT. 1. NORTH AMERICAN SAWFLIES — ROHWER. 15 



Oviposition. — The egg is laid in an incision in the axis of the leaf. 

 The incision is about 1.75 mm. long, enters the axis on the upper 

 side in the middle of the fluting, is slightly deeper apically where it 

 about reaches the center. In the living leaves these egg scars are 

 quite readily observed as the edges of the puncture or rip have a 

 yellow brown, dead, and frayed appearance. 



Egg- — length, 1.25 mm. ; greatest width, 0.33-0.4 mm. ; yellowish, 

 translucent, soft, gelatine-like, oval, somewhat larger towards the 

 cephalic end, thin skinned, the surface smooth to shiny. 



Larva (fig. 72). — In the earlier stages the head and spines are 

 blackish, but as the larva grows the head becomes tan in appearance 

 and the spines white. The head when appearing tan is greenish 

 with tan or pale brown spots (fig. 50) ; the eyes are in black spots 

 and the frons is spined medianly as well as marginally. The body 

 is pale green, very spiny, and with the elementary canal rather dis- 

 tinct and imparting a green hue to the translucent body. Annulet 

 A smaller than B and C and with but four pairs of spines ; annulets 

 B and C largest and with numerous spines; and annulet D smallest, 

 and spineless (fig. 60). The spines group themselves somewhat on 

 rather prominent areas which are arranged in a transverse row 

 across the segment. Legs semitransparent and 4- jointed. Uropods 

 on urites 2-7, urite 8 bare, urite 9 with a pair of small adventral 

 protuberances (doubtless uropods but not developed to the extent 

 of those on urites 2-7) and urite 10 with the postpedes. 



LABVAL INSTARS. 



The following series of descriptions record the appearance and 

 changes in the larvae of Cladius isomerus from stage to stage. A 

 comparison of the mandibles of an early second stage larva and a 

 full-grown larva reveal no fundamental differences. The mandibles 

 of the mature larva being generally larger and their teeth more blunt 

 and appearing worn, while those of the younger larva were long in 

 proportion to their width, with the teeth sharp and fine. 



Stage I (both sexes). — Body length, 2-3 mm.; head, 0.5 mm. high 

 by 0.4 mm. wide. Color : Body translucent white ; alimentary canal 

 greenish ; legs white ; spines long and black on head and body ; head 

 pale or faintly grayish; eyespots black. 



Stage II both sexes). — Body length, 2.5^ mm.; head, 0.6 mm. 

 high by 0.5 mm. wide. Color : Body whitish green ; spines of head 

 and body not conspicuously blackish ; head pale yellowish with black 

 eyespots. 



Stage III (both sexes). — Body length, 4.5 mm.; head, 0.76-0.8 

 mm. high by 0.6-0.7 mm. wide. Color: Body translucent greenish 

 white and shiny ; all spines black ; body spines longer than those on 

 3136— 22— Proc.N.M. Vol.60 3 



