2(i0 Ap^de and Pear Suclier 



(iii) Situation. These larvae are always found ou the open surfaces 

 of the leaves of the pear trees. Their responses to surroundings have 

 not been observed. 



(iv) Injurious effects produced by larvae. These effects are two- 

 fold : 



(a) Effects due to Cladosporium herbarium, the Sooty Mould. 



(6) Those due to the larvae. The larvae suck the juices of the 

 leaves and thus starve them. The leaf becomes curled and withered 

 and afterwards dries up. When the leaves die the metabolism of the 

 whole plant is interfered with and thus the plant mav ultimately be 

 killed. 



(3) TJie Adult. 



(i) The imago is green when it emerges from the nymph, but it 

 soon becomes dark in colour. The external structures with reference 

 to sex are identical with those of Psylla mali. 



(ii) Feeding habits. P. pyricola do not produce any. white spots 

 on the leaves, but on the other hand they produce rather injurious 

 effects. The adult insects secrete honey-dew and wet the surfaces of 

 the leaves, on which grows the same injurious fungus. 



Thus P. pyricola is injurious in both its stages, i.e. in the larval as well 

 as in the adult forms ; while P. mali is harmful only in the larval form. 



(iii) Reproduction. P. pyricola is tri-voltine; while P. mali is 

 uni-voltine, i.e. the former has three generations while the latter has 

 only one. 



The following are the probable dates of the three generations of 

 P. pyricola: 



1st generation . . . . April and May. 



2nd „ . . . . June, July. 



3rd ,, . . . . August, September. 



P. mali has only one generation from March to September, P. 

 pyricola hibernates in the imago stage. The adults of the third gener- 

 ation pass through the winter and lay eggs in the following spring 

 when the females are fertilised. P. mali hibernates in the egg-stage; 

 the eggs are laid in September and the larvae hatch out from them in 

 the following spring. In short, P. pyricola, when compared with P. mali, 

 seems to be as dangerous to pear trees. This pest is gradually spreading, 

 though at present it is only known locally. America and the Continent 

 suffer from this pest. It requires more working out. 1 have given its 

 description as a contrast to P. mali. 



