178 



HOW THE PSYLLA WAS INTRODUCED. 



The suddenness and severity of the appearance of tlie Psylla in 

 Maryland makes the question of its introduction one of considerable 

 interest. Upon inquiry it was develoi)ed that botli Mr. Emory and 

 Mr. Brown had procured pear trees from a nursery in New York 

 State in 1890 or 1891, and it is unquestionably from this source that 

 the Psylla was introduced. It will be remembered that this was just 

 at the time when the Psylla put in an appearance in such extra- 

 ordinary numbers in New York' State, as reported by Mr. Slingerland. 

 Mr. Brown told me that he had heeled in a lot of young pear trees 

 procured in the fall, near his house, for spring j)lanting. These 

 young trees were undoubtedly infested with hibernating Psylhis, 

 and it was in the immediate vicinity of the point where these trees 

 were heeled in that the outbreak occurred in this orchard. Mr. 

 Emory about the sanje time procured a lot of young stock from the 

 same nursery, and undoubtedly introduced the Psylla into his orchard 

 with these trees, coming as they did from a New York nursery at a 

 time when the Psylla outbreak was at its height in that State. In 

 further confirmation of this, Mr. Emory is confident, lie tells me, that 

 the present year is not the first one in which the Psylla has been pres- 

 ent in his orchard, and that he has observed indications for the last 

 year or two which he has now no doubt were evidences of the presence 

 of the insect. The multiplication of the insect in the orchard of Mr, 

 Brown was very rapid at the start, and its entire disappearance after 

 the first year is probably to be explained on the ground of some 

 peculiar climatic conditions which obtained in his neighborhood, but 

 di<l not extend northward to the orchard of Mr. Emory. Such condi 

 tions are.not unusual in the peach belt of Maryland, as illustrated by 

 the fact that orchards separated by only a few miles and in the same 

 conditions as regards soil and variety of fruit will seemingly be 

 affected by cold waves or storms, so that one will be barren while the 

 other will be full of fruit. 



THE FUTURE OUTLOOK. 



When suddenly confronted with an injury as unusual as this and 

 as startling- in its effects, one is naturally led to overestimate the 

 immediate damage and to take a too despairing view of the proba- 

 ble future. In the case of the pear-tree Psylla, however, I incline to 

 the belief that while the seriousness of the present damage can not be 

 questioned, the injury will be very much less in future, even if there is 

 not an entire cessation of the trouble and a disappearance of the pest. 

 The fact that this insect was imported into the United States with 

 pear trees over sixty years ago, and was long since widely distributed 

 throughout the pear districts of the northern States, and westward to 

 the Mississippi, and has yet, during all this time, rarely been reported 



