Ll. Lloyd 83 



were nearly mature. The numbers of the newly-emerged fell to a 

 minimum about June 8, and then again increased, and a similar fall 

 and rise occurred about August 17. These dates represent approximately 

 the beginning of the second and third broods of larvae of the year 

 respectively. The numbers of old larvae fell to minima about July 6 

 and September 7, and this indicates that the first and second broods 

 ended about these dates. As the infestation was getting out of hand in 

 August moth trapping was resorted to in the house, and 174 moths were 

 caught in this month, the numbers of larvae being much reduced at 

 the end of the month in consequence. It has been known that there 

 are two broods of larvae annually in the houses, since the reduction in 

 numbers between these, as represented in the diagram at the end of 

 June, is very noticeable to the observant grower. It has been a disputed 

 point whether there is a third brood, but a study of the diagram shows 

 that there is no doubt about this, at any rate in a favourable year. When 

 the mature larvae fall to a minimum at the beginning of September the 

 growing larvae of the third brood are very numerous and the demarca- 

 tion between the broods is thus obscured. 



The moths commence to emerge during February in houses heated 

 up in January, as in the house under consideration. The emergence 

 of the first flight continues to the end of May, and possibly later, being 

 at a maximum about the beginning of this month. The reasons why this 

 flight is so prolonged are : (1) the pupae do not respond equally to favour- 

 able temperatures; (2) they are in very different situations in the houses, 

 some being close to the pipes, and some almost at the temperature of 

 the outside air. 



The moths of the second flight began to emerge from pupae bred 

 from the first brood of larvae on June 4, while moths which were the 

 offspring of these commenced to emerge the first week in August, the 

 exact date being obscured by the slight overlapping of the second flight. 

 Probably all the pupae which survive the winter produce moths which 

 take part in the first flight. The very large majority of the offspring of 

 these form the second flight, only a few delaying emergence, and prob- 

 ably none in a uniformly warm spring. About a quarter of the offspring 

 of the second flight took part in the third flight in the present year, 

 while the remaining three-quarters delayed emergence. In a cold year 

 the second flight of moths might be so late that none of their offspring 

 would emerge to form a third generation. 



6—2 



