80 Habits of the Tomato Moth 



after their return to the tomato house, with pupation periods of 38—40 

 days. Six out of the 12 control pupae produced moths with pupation 

 periods of 20-32 days. In this case the chilling prolonged by about a 

 week the short pupation period of those which have emerged, and 

 apparently increased the tendency of the others to delay their emergence, 

 nine of those chilled, as against six of those unchilled, being still pupae 

 after 100 days. 



The three mature larvae which pupated in the cool room have not 

 emerged after 110 days, while in the control series of eight pupae ob- 

 tained from the same batch of larvae, three emerged after 17-23 days, 

 and five remain in the pupal stage. The chilling in this case seems to 

 have prevented the early emergence of any of the moths. 



In another experiment 30 pupae which had pupated August 1-5 were 

 divided into three lots of ten each and placed on moist earth in the 

 usual jars. One of these was put into a cucumber house, one into a 

 tomato house, and the third out of doors under a wooden box covered 

 by a folded heavy sack. The temperatures are given for the first month 

 following the pupation. That in the cucumber house was 70-4° (Range 

 59-104°), and of the ten pupae eight emerged after periods of 18-22 days, 

 one died, and one is still a pupa, after 120 days. In the tomato house 

 the temperature was 71-3° (Range 52-94°), and four pupae emerged 

 after 20-25 days, six still remaining in the pupal state. The temperature 

 to which those outside were exposed was 66-9° (Range 42-97°), and one 

 only emerged after a period of about 24 days, and the rest are still pupae. 

 The influence of the temperature was thus very marked, but the tendency 

 to prolong pupation was not abolished even by the relatively hot con- 

 ditions of the cucumber house. 



Some moths thus emerged in less than 50 days, and some after more 

 than 100 days, but there were no emergences between these limits. 

 At the end of April the glasshouses in this district were covered by 

 snow for two days, and the consequent chill probably accounts for the 

 long pupation periods of those insects which were nearly mature larvae 

 at that time. The tendency to prolong pupation reappeared in the 

 middle of a warm summer and became more intensified as the year 

 went on. Those responding to it correspond to those individuals of the 

 first brood in nature which do not emerge to form part of the autumn 

 flight of moths, but remain as pupae from the end of one summer to 

 the beginning of the next. Each pupa has thus an inherent tendency 

 either to emerge quickly or to hibernate. The experiments show that 

 an artificial raising of the temperature may reduce the tendency to 



