34-8 J- T. PATTERSON. 



3. Pupation, and the Emergence of the Imagines. 



Pupation in Copidosoma occurs during the first ten days of 

 August. The pupa stage lasts twenty-eight days. As stated 

 above, the larvae destroy all of the internal organs of the host, and 

 consume such portions as are dissolved by the action of their 

 salivary secretions. The undissolved portion consists largely 

 of the chitinous parts of the trachese. The larvae also destroy 

 all of the body wall except the superficial layer of chitin. During 

 the process of pupation the non-digested content of the cater- 

 pillar hardens and forms the thin-walled, oval chambers in which 

 the parasitic larvae lie and in which they undergo their trans- 

 formation into pupae. The superficial layer is perfectly trans- 

 parent, and at first is very flexible. Later, as drying occurs, it 

 shrinks in on the walls of chambers and becomes hard and rigid, 

 the whole forming the typical mummified carcass (Figs. 2, 4, 6). 

 Practically all of the pupae are oriented in a definite fashion in 

 the carcass. Their heads are directed toward the anterior end 

 of the carcass. Just before becoming immobile, the Gnorimo- 

 schema larva almost invariably turns the head upward in the 

 gall chamber; likewise, the parasitic larvae, just before pupating, 

 orient themselves so that their heads are directed upward, in the 

 direction of the anterior end of the carcass. 



The imagines come out during the last week of August and the 

 first week of September (Table I.). They escape by gnawing 

 holes through the walls of the chambers and the superficial 

 chitinous layer, both of which become very fragile. As a rule 

 they all emerge practically at the same time. Several cases 

 have been observed in which the entire brood has escaped within 

 a period of ten minutes. 



Once free from the carcass, they immediately gnaw a hole 

 through the wall of the gall. Their escape is greatly facilitated 

 by the habit of the caterpillar, just before becoming immobile, 

 of eating out a passage-way to, or nearly to the epidermis of the 

 plant. But in no case does the parasitized caterpillar secrete 

 a silken plug. Hence, in order to escape to the exterior, the 

 parasites have only to cut through the remaining thin portion of 

 the wall. 



The parasites must winter over in the imago state; otherwise 



