Galls caused by the larvae of Diplosis pyrivora Riley 



on 



the fruit of Pyrus communis Linn. 



PLATE 123. 

 Synonymy of Insect. 



Cecidoniyia nigra(?) Meigen, Schmid., Theobald. 

 „ pyricola(?) Nardli. 



Habitat of the Pear-tree.— The pear here referred to is 

 one of the many cultivated kinds found in orchards and 

 kitchen gardens — viz. Catillac. 



The Gall is formed by the premature and abnormal 

 swelling of the young pear, causing it ultimately to turn 

 black, shrivel, and fall from the tree. 



Manner of Growth. — Each young pear forms a separate 

 gall. 



Colour. — The normal colour of the young pear. 



Average Dimensions of a Mature Specimen. 

 Girth, 36 mm. 



May be sought during the months of May, June, and July. 



The Growth is complete by the end of June. 



The Typical Condition of the gall is multilarval. 



The Larv^ pupate in the ground. The imagines emerge 

 during May. 



The parent insect oviposits in the pear blossom as soon as 

 the petals show themselves. A dozen or more ova are laid, 

 from which larvse quickly hatch. These immediately begin to 

 eat their way towards the centre of the embryo pear, which, by 

 reason of the irritation, increases rapidly in size, ultimately 

 splitting open and falling to the ground. 



The gall is also figured by Miss Ormerod, " Handbook of 

 Insects," 1898, p. 120. 



The illustration is of specimens kindly given to the author 

 by the Rev. E. N. Bloomfield, M.A., F.E.S., from his garden at 

 Guestling, Hastings. 



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