Ll. Lloyd 73 



maining larvae of the batch were kept in the jar and were supplied 

 with fresh tomato foliage every day or two. No' disease was apparent, 

 but on the 14th day 25 only remained alive; on the 23rd day 16; on the 

 38th day, 3, which were all very small. On the 52nd day one was still 

 alive but was very feeble and not one-third grown. It had apparently 

 not fed for some days and appeared to be dying. It was still kept in 

 the same jar and was supplied with knotgrass. The following day it 

 was seen to be feeding on this, and a week later was growing fast. On 

 the 75th day after leaving the egg it became mature and began to spin 

 its cocoon. It was then perfectly healthy and weighed -96 g., a weight 

 which is above the average of the mature larvae. 



(b) A small batch of eggs, laid by a moth obtained from the tomato 

 houses, was divided into four equal parts, each part containing about 

 15 unbroken eggs. When these were about to hatch they were placed 

 on four plants growing in pots, enclosed in muslin sleeves, and kept 

 on the ground in the tomato house. The plants used were knotgrass 

 (Polygonum aviculare), white goosefoot (Chenopodium album), bittersweet 

 (Solatium dulcamara), and tomato. (The bittersweet is the commonest 

 weed in the tomato houses, and one upon which the moth frequently 

 oviposits. The foliage often shows marks where the larvae have fed, 

 but they are very rarely found upon it.) The larvae were transferred 

 to fresh plants during their growth when necessary. After the first week 

 of life they were removed every day or two and weighed, the average 

 weight of those on each plant being plotted in a diagram. The history 

 of these four lots of larvae is as follows : 



1. On knotgrass 12 larvae commenced to feed. Their growth was 

 rapid and uninterrupted. One was accidentally crushed and the re- 

 mainder attained maturity between the 20th and 22nd days of active 

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



2. On goosefoot nine larvae commenced to feed. Their growth was 

 rapid but rather less so than on knotgrass. Two died without any disease 

 being apparent. The flacherie disease appeared among them and five 

 died of this, two pupating on the 23rd and 27th days of active 

 life. 



3. On bittersweet ten larvae commenced to feed and survived the 

 15th day, growth being very slow but rather more rapid at first than 

 on tomato. They then began to die off though there was no apparent 

 disease. On the 28th day one only survived, and had a weight of -08 g. ; 

 on the 29th day, -07 g. ; on the 30th day, -055 g. Like the rest of this 

 batch it was apparently starving to death, and though it was transferred 



