456 FORTY-EIGHTH REPORT ON THE STATE MUSEUM 



How the Attack may be Recognized. 

 The attack can be recognized by comparison with the features given 

 above and in other publications on it. Its identification must usually 

 depend upon the characters shown in the galls or blisters. The mite 

 producing them, even when traveling on the surface of the leaf, is 

 invisible to the naked eye, and can only be seen with the aid of a high 

 magnifying power. Using an achromatic triplet, when some infested 

 leaves sent to me were carefully examined, three or four of the 

 four-legged, long, white mites could be distinctly seen moving rather 

 rapidly over the surface. 



Is the Kiefifer Pear Particularly Liable to Attack. 



A gentleman writing to the Country Gentleman from Haddonfield, 



N. J., in 1894, makes the following statement: 



Enclosed are leaves from Kieffer pear-trees planted in the spring of 

 1893, and two years old when planted. The trees are vigorous and 

 green, but some of the leaves are shriveled and marked in blotches of 

 a reddish-brown, as the inclosed show. Other leaves on the same 

 branch are healthy. Will you inform me what the trouble is, and 

 how to remedy it ? I have two thousand trees of this age and, as far 

 as I can see, the Kieffers are the only ones affected. 



Another gentleman, writing from Charlotte, N. C , sends leaves of 

 four-year-old LeConte pear-trees which show a severe attack of the 

 blister galls. 



Another correspondent, from Carlton, N. Y., has written: *' Find 

 inclosed Bartlett pear twigs and leaves. Can you inform me what the 

 disease is and what causes it, and if there is a remedy for it ? There 

 is a dwarf Duchess planted by the side of the Bartlett that does not 

 seem to be affected with this mildew or rust, or whatever it is." 



It will probably be found that the mite will attack all or most of the 

 varieties of pear without special preference, such as the pear-midge has 

 shown for the Lawrence pear. 



Its infestation of a single tree in an orchard may be the result of its 

 having been accidentally carried to it bj' the wind or upon a bird or 

 insect, as the San Jose Scale insect is known to be conveyed. Should 

 the mites fall to the ground with the leaves, they would not probably 

 survive the winter; and it is hardly possible that they would travel 

 from one tree to another unless by contact of interlocking branches. 



Characters of the Phytoptidae. 

 The Phytopticlce, the family to which the pear-leaf blister-mite 

 belongs, are 'popularly known as gall-mites from the deformities that 



