THE POTATO TUBER MOTH. 



39 



laiTa seldom escapes. The parasitized tuber-moth larva is readily de- 

 tected when it becomes mature and seeks a place to pupate. A large 



chirk or redcUsh spmdle is apparent, filling most of its abdomen, and the 



larva is very restless and seldom stays in one 



place long enough to spin a cocoon. Finally 



the host loses all power of locomotion and dies, 



and within a few hours the mature parasite 



larva (fig. 26) forces its way through the skin of 



its host and begins spinnmg its cocoon (fig. 27)- 



As the parasite larva is ahiiost the size of its 



host, only one develops on each tuber worm. 

 The cocoon is completed within a day or two. 



It is very heav}^, ellipto-C5dmdrical in shape, 



light gray, and with a lighter band around the 



middle. The pupa, 

 removed from its co- 

 coon, is shown in fig- 

 ure 28. 



This parasite assisted greatly in reduc- 

 ing the mnnbers of the tuber moth in the 

 potato tops during 1914 and 1915. 

 An average life cycle is given below : 



December 15, 1914. — Tuber-moth larva parasitized 

 by Carnpoplex phihorimaeae . 



February 5, 1915. — 1 Campoplex phthorimaeae adult 

 issued. (Male.) 



February 6, 1915. — 1 Campoplex 

 phihorimaeae adult issued. (Female.) 



Life cycle 52 days at an average 



F. 



Fig. 26. — Campoplex phfliori- 

 macac; Lateral view of ma- 

 ture larva with view of face. 

 Much enlarged. (Original.) 



Fig. 27. — Cocoon of Campoplex phtho- 

 rimaeae, parasite of potato tuber 

 moth. Much enlarged. (Original.) mean temperature of about 54 



HABROBRACON JOHANNSENI VIER.^ 



This is probably the best known parasite of the 

 tuber moth, both where it occurs as a leaf -miner and 

 as a pest of stored potatoes. It is wcU distributed, 

 having been reared from tuber-moth material" collected 

 over most of southern Cahfomia. 



It oviposits in the mature larva of the tuber moth 

 after it has spun its cocoon. As many as 13 parasite 

 liirvsc have been observed to develop on a single host. 

 The adult female is very active, })ut seems to prefer 

 to work oidy in the light, for the parasite has never 

 been resired from material k(!pt in darkened bins. 



The larvaj may develop eitJier ext(irnally or internally, the host 

 seeming to depend on the position of the egg. Aft(!r the tuber-moth 



Fig. 2S.— Campo- 

 plex phihorimaeae: 

 Lateral view of 

 pupa. Much en- 

 larged. (Original.) 



> Chittenden Nu. 2230o«. 



