New York Agricultural Experiment Station. 435 



oviposition of the hibernating brcod of " flies " 



The eggs of the pear psylla are of small size and the act of 

 oviposition is seldom observed owing to the smallness of the insects. 

 At the beginning of oviposition the trees were dormant and the 

 eggs were laid on the wood in crevices in the bark around the bases 

 of the blossom buds or on the stems. The habit of the " flies " 

 of collecting in large numbers on water sprouts often resulted in 

 noticeable quantities of eggs being deposited on such growth and 

 in 1910 they were sufficiently numerous in these locations to attract 

 the attention of orchardists to the infestation. Eggs were the most 

 abundant on the under side of twigs and small branches, which 

 appeared to be due to the protection from cold and winds afforded 

 to the " flies " by these situations. 



The young foliage was sought by the " flies " as a place of 

 deposition for their eggs as soon as the buds opened, and as the 

 season advanced belated adults deposited eggs only on foliage. 

 The psyllas seemed to choose by preference the midrib of the leaves 

 and blossom stems for that purpose. Young fruit stems also were 

 selected by them for the lodgment of their eggs. These normally 

 were comparatively few in numbers and resulted in little or no 

 serious infestation of the foliage. 



Egg-laying usually began within a few days after the spring 

 migration of adults from winter quarters occurred and extended 

 over a period of several weeks. Most of the eggs, however, were 

 usually deposited within two weeks from the time oviposition com- 

 menced. In 1910 a large number of the eggs were laid about April 7. 

 The greatest numbers of eggs in 1911 were seen on April 30, while 

 in 1912 most of the eggs were deposited before April 26. In 1913 

 they were abundant on April 1 with only a slight increase later 

 in the month. 



As to the time required for the hatching of these eggs Slinger- 

 land 11 states that in 1892 eggs were being deposited on April 7, 

 some of which were taken to his office where they hatched in eleven 

 days. At Geneva some laboratory breedings of psylla eggs were 

 made during 1911, the results of which are presented in the 

 following table. 



"Cornell Univ. Expt. Sta. Bui. 44:168. 1892. 



