Ll. Lloyd 71 



plants in the nurseries. Five experiments were carried out, in which 

 about a hundred moths were used. The batches of eggs were removed 

 and counted every few days. The results of the experiments are shown 

 in Table II, in which the percentages of the batches of eggs laid on the 

 various plants in each trial are given. 



Whenever the common weed "white goosefoot" (Chenopodium album) 

 was included, the moths showed a distinct preference for it over the 

 other plants. This preference appears to be about two to one as com- 

 pared with tomato when equal foliage is exposed. The attraction is 

 insufficiently powerful to give appreciable benefit, since a trap crop 

 could not be a bulky one. Experience subsequently gathered in the 

 nurseries confirms this. Chenopodium is a common weed in the houses 

 and, where the infestation is heavy, it is stripped of its foliage by the 

 larvae. Where the infestation is light, it is rarely discovered by the 

 moths. No experiments on a practical scale were therefore carried out 

 on these lines. 



(ii) The Egg. 



The egg is flattened and strongly ribbed, without any distinctive 

 markings. Its colour varies at the laying through various shades of 

 green to almost white. During incubation it becomes yellow, and a few 

 hours before hatching, it turns black owing to air entering the shell. 

 The eggs hatched in seven or eight days at mean temperatures varying 

 from 67 to 80° F. All the eggs in a batch hatch within a few hours. 



(iii) The Larva. 



The newly hatched larvae eat part of the egg shells and then com- 

 mence to feed od the lower surfaces of the leaf on which the eggs were 

 laid. They do not eat completely through the leaf until they are more 

 than a week old. They feed mainly during the night and remain 

 quiescent on the plants in the daytime. At first they drop readily by 

 threads if disturbed, but later this habit is lost. During growth they 

 cast their skins five times, a sixth moult taking place at the pupation. 



In its first three skins the larva is always green and may retain this 

 colour throughout its active life. In other cases at the fourth or fifth 

 moult it may take on a lighter or darker shade of brown, and occa- 

 sionally it becomes somewhat reddish. Yellow larvae and some almost 

 white have also been seen. The skin is closely speckled with white 

 spots, and the hair bases appear as conspicuous black spots on the back 

 and sides. The spiracles are white, with a black spot before and behind, 



