The Canadian Horticulturist. 



87 



THE PEAR TREE PSYLLA. 



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E briefly referred to the pear tree psylla, in our 

 report of the Rochester meeting, as being one 

 of the most dreaded enemies of the pear grower. 

 It was imported from Europe upon some young 

 pear trees in 1832, by Dr. Plumb, of Salisbury, 

 Conn., and it has gradually spread over the 

 United States until it has reached the Missis- 

 sippi Valley, and it is quite abundant in some 

 parts of New York State. Mr. Powell, an exten- 

 sive fruit grower of Ghent, New York State, 

 reports that in 1892 these insects reduced his 

 pear crop from an estimated yield of twelve hundred barrels to an actual yield of 

 less than one hundred barrels of marketable fruit. The indications of its 

 presence are the stunted growth of the trees, withering of young shoots, sickly 

 appearance of the trees, the leaves turning yellow and the fruit stunted in 

 growth, which after midsummer fall from the tree. A fluid, called honey dew, 

 accompanies their presence upon the trees. 



Mr. Slingerland, who published a bulletin from the Cornell Experiment 

 Station upon this insect, states that an orchard which he visited in November, 

 1 89 1, presented a deplorable appearance as though scorched by fire. 



Fig. 517 represents an immature form of the insect, or nymph, and fig. 518 the 

 adult form, much enlarged ; the actual length being indicated by the line at the 

 side. When first hatched, it is a translucent yellow, scarcely visible to the naked 



Fig. 517. — Full-grown Nymph, 

 Dorsal View. 



Fig 518. — Adtlt Insect. 



eye; eighty of them placed end to end would scarcely measure an inch. They 

 gradually increase to nearly four times this size. In about a month the nymph 

 changes to the adult insect, the full-grown nymph very much resembling a 



