THE REPOET OF THE No. 36 



Reproductive Period of Female: The average reproductive period of IT females 

 in 1917 was about 30 days and in 1918 with 15 individuals it was 36 days, the 

 maximum and minimum for both seasons being respectively 63 days and 16 days. 



Length of Adult Life: Our observations indicate that the average length of 

 life of the male is about 5 weeks and that of the female a few days longer. 



The Overwintering Adult. 



Description : The overwintering adult can be readily distinguished from the 

 summer adult by its larger size, darker coloration, and by its transparent front 

 wings. The predominating colour of this form is black or dark brown. The female 

 is about 2.43 mm. in length and the male about 2.16 mm. 



Habits : In September, with the coming of autumn, the overwintering forms 

 commence to appear, and their production is continued until the close of the 

 season. They feed to some extent but do not mate or lay eggs. During the 

 winter they hibernate chiefly beneath the rough bark of the trunks and main 

 limbs and also under grass, leaves and rubbish near the infested pear trees. In 

 late March of early April, with the coming of warmer weather, they leave their 

 winter quarters, congregate on the twigs and fruit spurs chiefly in the lower 

 central portions of the trees, and in a short time, provided the weather remains 

 propitious,- they mate and commence to lay eggs. They die off rapidly in spring, 

 and by the time! the fruit buds have burst comparatively few of them are left 

 on the trees. A few stragglers survive until after the blossoms have fallen. 



Egg Laying Period: The females usually commence to oviposit early in April, 

 and, by the time the fruit buds have burst, most of the eggs have been laid. Belated 

 individuals continue to oviposit up to the falling of the petals in late May or 

 early June. 



Reproductive Capacity of Female: In an experiment with -i couples, the egg 

 production per female varied from 121 eggs to 448 eggs, with an average of 279 

 ■eggs. Each female laid from 1 egg to 48 eggs per day. 



Number of Generations. 



In our insectary studies we obtained a maximum of four from the earliest 

 laid eggs and a minimum of two generations from the last laid eggs. This would 

 indicate, at least theoretically, that in the Niagara district there are two complete 

 generations, a very large third generation and a small fourth generation. 



Control. 



Natural Control. 



Several species of insects, notably ladybird beetles, attack the psylla and check 

 its rapid multiplication to some extent. However, undoubtedly the most impor- 

 tant control agency afl'orcled by nature is the weather. Our observations indicate 

 that protracted periods of cold, wet weather in spring may be disastrous to the 

 loggs and newly hatched young. Hodgkiss records the destruction of hibernating 

 iforms in spring by ice storms, heavy washing rains, and sudden changes in tem- 

 perature. Professor Brittain, in a letter dated September 23rd 1918, reports a 

 great diminution of the psylla in Nova Scotia, which he thinks was caused by the 

 hard winter of 1917-18. Long spells of hot, dry weather also appear to be fatal 

 to many psyllas chiefly, we think, because such weather renders much of the 

 foliage hard and dry and therefore unsuitable for the development of nymphs. 



