Feb. 15, 1921 Leconte's Sawfly, an Enemy of Young Pines 749 



SIXTH INSTAR 



In this instar the larva grows from 18 mm. to about 22 mm. For 

 characters, see previous detailed descriptions of larva. 



PREPUPA 



The prepupa, or seventh larval instar, is the nonfeeding, cocoon- 

 spinning stage in which the larvae search out a suitable place to spend 

 their quiescent period. In size they usually measure from 10.5 mm. for 

 one which has spun a male or small type of cocoon, to 12 mm. for one 

 which has spun an average size large type or female cocoon. 



HEAD 



Structural characters. — The head is 2 mm. in height (dorsad- 

 ventrad) by 1.6 mm. broad, and except for being somewhat smaller is 

 similar to that in the preceding, or sixth, stage. 



Color. — The head is pale whitish, usually grayish across the dorsum 

 above the eyes. The eyes are pale and are placed somewhat dorsad- 

 caudad of the center of the black oval spot surrounding them. The 

 antennal joints are inconspicuous, being yellowish white on a white 

 membrane. The frons, adfrons, clypeus, labrum, labium, and maxillae 

 are all pale, the heaviest chitin appearing only yellowish white while the 

 mandibles are pale excepting the teeth, which are brownish black. 



thorax 



Structural characters. — The thorax is similar to that of the sixth 

 stage larva. 



Color. — The thorax is about the same as that of the sixth stage 

 except that the skin is pale white rather than yellowish white, with spots 

 grayish black rather than black; the mesothoracic and metathoracic 

 subdorsal spots are absent on fold C and very faint on B; and the legs 

 are entirely white. 



ABDOMEN 



Structural characters. — The abdomen is similar to that of the sixth 

 stage. 



COCOON 



The cocoon is a tough, single- walled, papery, red-brown cylinder with 

 hemispherical ends. The exterior, which is darker and less glossy than 

 the interior, shows some coarse threads and often has particles of sand 

 or other surroundings adhering to it. The cocoons vary in size for both 

 sex and individuals. In a number examined, the female, or larger 

 cocoons, varied from 9.5 to 11 mm. in length and from 4.5 to 5 mm. in 

 diameter, averaging 10.3 mm. long by 4.6 mm. in diameter. The male, 

 or smaller cocoons, vary from 7 to 7.8 mm. in length and from 3.2 to 3.5 

 mm. in diameter, averaging 7.5 mm. long by 3.4 mm. in diameter. 



