330 THE CANADIAN ENTOMOLOGIST. 



1888, with a fruit grower at Marlborough, N. Y., regarding what was 

 doubtless this same Plum-twig Gall-mite. In this instance the galls also 

 occurred along cracks on the bark of larger limbs, and in close connection 

 with the Black Knot fungus, which was, of course, accidental. Again in 

 1891, Dr. Riley (Insect Life, Vol. V., p. 17) records a small mite as 

 injurious to Damson plum trees at Berlin Cross Roads, Ohio. This was 

 probably the mite under discussion. These are the only records I have 

 found in American literature of any mite making galls on plum-twigs. 



There has recently appeared in the European literature three admir- 

 able and exhaustive papers on the Phytoptidae, by Dr. Alfred Nalepa 

 [Sitz. der Math.-Natur. Classe der kais. Akad. der Wiss., Abtheil. I., Vol. 

 96 (1887), pp. 1 15-165; Vol. 98 (1889), pp. 11--156; Vol. 99 (1890), 

 pp. 40-69]. Each article is accompanied by several finely executed 

 plates. *Luckily, I had access to Dr. Nalepa's work, and I found that 

 but one Phytoptid had been described which lived in galls on the twigs 

 of plum trees. In Vol. 99, p. 54, he describes and figures this mite as 

 Phytoptics phlxocoptes. In figure 2, 1 have reproduced (photographically) 

 one of Dr. Nalepa's figures of the mite ; it is the female and is magnified 

 450 diameters. The mites in the galls were very similar to, if not iden- 

 tical with, this European species. The only noticeable difference is in the 

 shape of the body. The Pennsylvania mites are shorter and wider, but 

 this may be quite possibly due to their being in hibernation and dormant. 

 The European species was first described and figured as primi, by 

 Amerling, in 1868. 



Tlie mites could have been easily introduced into this country on 

 plum stock, but the correspondent writes that his trees were grown in his 

 vicinity " and are known as sucker-growth trees." If our mite is identical 

 with the European species, and it probably is, the pest was introduced 

 into this country some time previous to 1887, and it is now present in 

 New York, Ohio, and Pennsylvania. 



The fruit grower informs me that his trees are thrifty, but the fruit is 

 undersized. So many thousands of the little creatures working at the 



*Dr. Nalepa puts our knowledge of the Phytoptidse on a scientific basis. He 

 rightly discards all previous descriptions of the mites as inadequate and not definite 

 enough for the determination of any species. He gives new detailed descriptions with 

 excellent figures ; and the species are renamed, usually with new names, but sometimes 

 the old names are retained, as in the case of the Pear-leaf Blister-mite, which he calls 

 Phytoptus pyri, n, sp. We should thus write //r?, Nalepa, instead oi pyri, Scheuten. 

 Dr. Nalepa's work should be in the hands of every one interested in the Phytoptidae. 



