Entomological Depaetment. 325 



Phytoptics, to which this pear pest belongs, differ, however, from all 

 other mites in that they never possess but two pairs of legs.* 



The popular name for this pear pest that has come into general use 

 is the Pear Leaf Blister Mite. Crawford called it the Pear Phytoptus, 

 the Anglicized form of its scientific name Phytoptus pyri. 



The Distribution atid Past History of the Mite. — The cause of this 

 peculiar affection of pear leaves was discovered by Scheuten, a Ger- 

 man, in 1857; doubtless the disease itself had been observed many 

 years previously. Later German writers, Sorauer in 1873 and 1886, 

 Kaltenbach in 1874 and Frank in 1880, speak of the disease as com- 

 mon in Europe. In 1877 Murray records it as common in England 

 and on the continent. Crawford states that public attention was first 

 called to the pest in South Australia in 1881. In 1891 French found 

 it had gained a foothold in Victoria orchards. In 1888 Fletcher 

 received specimens of the disease from Nova Scotia, and in 1891 he 

 found it was very widespread and serious throughout Canada. These 

 are all the references to the occurrence of the pest in other countries 

 that we have seen. 



The first record of the appearance of the disease in the United 

 States is in 1872, when Glover found it common in Maryland. In 

 1880 Burrill said the disease was widespread in this country. Osborn 

 found the mite in large nitmbers on some Russian pear trees in Iowa in 

 1884. Pie thought the pest had probably been introduced with the 

 scions of the trees recently imported from Europe. In 1890 specimens 

 were sent to Dr. Lintner from Charlotte, N. C, with the report 

 that the disease was very prevalent there. In 1891 we received 

 the mites from a correspondent in Fayetteville, Ark., who said his 

 trees were badly affected. At the meeting of the Association of 

 Economic Entomologists in 1892 Webster of Ohio and Smith of New 

 Jersey reported the pest as very abundant in their respective States 

 that year. This year McCarthy has found the disease very prev- 

 alent in the orchards of North Carolina. 



In 1889 and 1890 the pest was abundant in pear orchards in western 

 New York. We received specimens from Oswego in 1891; and Dr. 



* These curious four-legged mites seem to have been first observed in 1834 . 

 For seventeen years they were thought to be immature forms of some oight- 

 legged species. In 1851 Dujardin (An. des Sci. Nat., 3d Ser., vol. 15, p. 166) 

 showed why he believed them to be adult forms and proposed the generic 

 name Phytoptus for such four-legged forms. In 1857 Scheuten, who described 

 the Pear Leaf Blister Mite, criticized Dujardin's work and adhered to the 

 theory that they were but immature forms. During the succeeding twenty 

 years several observers studied the four-legged mites, and since 1877 it has 

 been the prevailing opinion that they are adult animals forming a distinct 

 family among the mites. 



