854 



Journal of Agricultural Research 



Vol. VI, No. 28 



Fig. 7. — Thersilochus conotracheli: Full-grown larva, or fifth 

 instar. Much enlarged. 



an acute, fairly strongly chitinized point. They are about 0.06 mm. long. 

 The fourth molt takes place when the larva is about 4.75 mm. long. 



Fifth instar. — The fifth 



instar (fig. 7) is a somewhat 

 enlarged replicaof the fourth, 

 with the mandibles and 

 other mouth parts more 

 heavily chitinized and some- 

 what larger. The mandibles 

 are of nearly the same form 

 as those of the fourth instar, 

 but are about 0.074 mm. in 

 length. In this instar also 



the ridges supporting the mouth parts are strongly chitinized and can be 



faintly seen through the skin, especially the one extending from the base of 



the mandible around to the 



sides of the head. (See fig. 



8.) Immediately after the 



molt this instar is about 5 



mm. long, and at full growth, 



after it has left the body of 



its host and entirely con- 

 sumed the fluid contents, 



it has reached a length of 



about 7 mm. 



Fig. &.— Thersilochus conotracheli: Face of full-grown larva: 

 a, Labrum; b, mandible; c, maxilla; d, maxillary palpus; 

 e, labium; /, labial palpus. Highly magnified. 



THE PUPA 



The pupa (fig. 9) is stout, about 4.5 mm. long, 

 and in the female has the ovipositor curved up 

 over the back and reaching about two-thirds of 

 the way to the thorax. The abdomen is about 

 two-thirds as deep as long and is much stouter 

 than and nearly twice as long as the thorax. 

 The thorax is blocky, with the rather small 

 head situated near the ventral anterior margin. 

 The antennae reach to about the middle of 

 the abdomen and the hind legs nearly to the 

 apex. The abdomen of the male pupa is 

 terminated by three lobes, one dorsal and two ventral, the latter repre- 

 senting the genital armature of the adult. 



Fig. 9. — Thersilochus conotracheli: Pupa 

 of female, and apex of abdomen of 

 male pupa. Much enlarged. 



