10 BULLETIN 1028, U. S. DEPARTMENT OF AGRICULTURE. 



cocoon the maggot pupates and casts its larval skin, which is pushed 

 back to the posterior end of the cocoon over the previously voided 

 material. 



The third-stage maggot (PI. I, I) of the summer generation has 

 quite a different cycle. After having completed its cocoon, in which 

 it is to hibernate, it becomes shorter and stouter, measuring about 

 4 mm. in length. It is a pale lemon yellow, and remains quiescent 

 until the following spring. About the time when the first gipsy 

 moth eggs hatch, the maggot resumes acti\dty, first voiding the ac- 

 cumulated waste in the caudal end of the cocoon. Two or three clays 

 later pupation takes place, and the larval skin is cast and pushed to 

 the caudal end of the cocoon, as in the spring generation. 



Pupa. 



The pupal stage last's from five to nine days. About two days after 

 the completion of the cocoon the larval skin is cast. The pupa is 

 whitish with long appendages and has a movable abdomen. The 

 eyes soon begin to darken, the ocelli are disting-uishable, and the 

 thoracic and abdominal segtnents take form. The mouth parts, an- 

 tennae, legs, and recurved ovipositor are plainly seen. In three or 

 more days the development is complete. The whole is now dark, 

 nearly black. The pupal skin is cast and the adult lifts the cocoon 

 cap, having cut around its base, which was left weak by the spinning 



larva. 



Cocoon. 



When the third-stage maggot is about two-thirds of its way out 

 of the host, it begins to construct its cocoon. The first few threads 

 seem to be attached ventrally to the maggot itself on the last seg- 

 ment which is outside of the caterpillar. After making an attach- 

 ment at this point the maggot straightens out horizontally, then 

 swings back underneath itself again and makes another attachment. 

 It continues this process laterally and dorsally, spinning all the 

 while and forming loops which it gradually fastens securely in a 

 similar manner. As the outer loose cocoon is developed, the maggot 

 must break away from the original attachments and gradually work 

 itself entirely free from its host. The maggot reverses its position 

 several times during the construction of the cocoon. When com- 

 pleted, the cocoon is about 5mm. long and is composed of an outer 

 loose covering of fine threads, some of which are attached to the 

 host or any object on which it may rest. Just within this is a tough, 

 tightly woven envelope, which encases a very fine smooth inner sac 

 next to the maggot. The cocoon is slightly flattened on its ventral 

 surface and convex laterally and dorsally. The anterior end is 

 rather fiat. The cap, which is thinner along its base, is at the ante- 

 rior end. The posterior end is slightly pointed. It takes the spring- 



