Ll. Lloyd 



75 



on cut Chenopodium and half on cut tomato foliage, in glass tubes in 

 a tomato house. Six larvae commenced to feed on the Chenopodium 

 and grew rapidly, all maturing between the 24th and 28th days of active 

 life. Their growth is represented by the dotted line in Diagram II. 

 Eight larvae commenced to feed on the tomato foliage, and two of these 

 died without showing signs of disease. The remaining six became mature 

 on the 34th and 35th days. Their growth is represented by the con- 

 tinuous line in Diagram II. Though the development was uninterrupted 

 it occupied on the average nine days longer than on Chenopodium. 



Larvae were reared from the egg on Polygonum and Chenopodium 

 and transferred in various stages to tomato foliage and fruit. In ten 



% pupated 



m o m o m 



»- <N <N CO CO 



Age in days 



Growth on larvae on: — 



Chenopodium Tomato 



Diagram II. Contrasting the growth of a batch of larvae on Chenopodium and tomato. 



experiments, 110 larvae, from two to three weeks old, were used in 

 this way. None of these reached maturity, though many of them fed 

 and some made considerable progress. It was not concluded that the 

 larvae in the houses could never pass from these weeds to tomato, but 

 only that such transfer would not be common. On the other hand larvae 

 collected from tomato were very frequently transferred to a diet of 

 Chenopodium, Polygonum, Rumex, cabbage and lettuce, on which foods 

 they invariably matured normally. 



These experiments are sufficient to show that in some way a diet of 

 tomato foliage alone is not suited to the majority of the larvae, which 

 therefore require a change of food before they can mature. There is 



