199 



Bummer progresses they turn to corky blister-like galls, with a hole in the centre, 

 through which large numbers of minute mites issue and attack fresh parts of the leaf. 



I am not aware that this injury to pear trees has ever as yet been recorded 

 in Canada ; but I find that it is very widespread and serious. Four years ago 

 I received specimens from River John, Nova Scotia, and during the past summer it 

 has come in from several different localities. It is a European insect, and has 

 doubtless been imported with pear trees. 



" May 28, 1889. — The enclosed pear leaves were gathered off a pear tree in 

 the garden. I noticed the young pear trees had their leaves flagging, and upon 

 enquiry was told that it was a blight, and no one knows it nor how to cure it. Is 

 this the case ? " 



" October 15, 1891. — I send you some more of the pear leaves. They are not 

 nearly so much diseased this year as usual." — Mrs. W. (r. Schreiber, Springfield-on- 

 Credit, Ont. 



" June 22. — I mail to your address some infested pear leaves. The disease is 

 different to our common enemy Fusi da diUm. This trouble has been quite common 

 in our pear orchards and spreads rapidly under favourable circumstances." 



"July 13. — Enclosed I send some more diseased pear leaves, as requested. 

 This trouble on the pear leaves, not directly injuring the fruit, we have given it but 

 a casual passing notice. But every year it is growing worse, and on many of the 

 trees this year the foliage is so impaired that the vigour and health of the trees are 

 very much injured." — J. K. MacMichael, Waterford, Ont. 



" July 14. — I send pear leaves attacked, I suppose, by insect or fungous 

 disease." — Rev. P. J. H. Axford, Cornwallis, N. S. 



"August 24. — Some kind of blight has been affecting the pear trees in my 

 orchard for the past two or three years. I enclose some leaves, and should be much 

 obliged if you could inform me of the cause of the appearance of these leaves, and 

 also if there is any remedy. A good many of the trees are dying off, and I cannot 

 attribute this to any other cause than the blight." — Chas. A. Holmes, Richmond 

 Hill, Ont. 



" September 8. — I enclose you some diseased pear leaves sent to me from 

 near London. Would you be kind enough to tell me what the trouble is with them. 

 I have seen the same before, and understand the insect to be a very small mite." 

 L. WooLVERTON, Grimsby, Ont. 



This injurious disease, which has spread unnoticed over the Dominion and much 

 of the United States, has not been treated of by many of our North American 

 entomologists, although the mite was figured by Glover (U. S. Agric. Rep. 1872) 

 and mentioned by Riley (Am. Ent. Ill, p. 26), and Osborn (Ag. Col. Iowa, Bui. 2, 

 1884). Prof. J. H. Comstock, in Cornell University Bulletin XXIII, December, 1890, 

 gives a full and well illustrated account of this pest, and in the Handbook of Destruct- 

 ive Insects of Yictoria (Australia), by C. French, F.L.S., F.R.H.S., the Government 

 entomologist, is also another good account, illustrated by a coloured plate, giving its 

 history in the Australian colonies. 



The cause of this disease, which, until it 

 18 examined, is as a rule attributed to the 

 attacks of some fungous parasite, is a very 

 minute insect belonging to the gall mites, Phy- 

 toptidce. It is a very small insect indeed, 

 with an elongated body, shown very mach 

 enlarged at Fig. 6 ; it is so exceedingly small, 

 .12 mm., that it requires to be examined under 

 Fig. 6.— Adult mite. a microscope. The life histoiy as sketched 



(Kindly lent by Prof. J. H. Comstock.) ^y p^.^^f- Qomstock is as follows :— 



" Life history of the Species. — The eggs are laid by the females within the galls 

 that they have formed and here the young are hatched. How long the young 

 remain within tHf gall of their parent has not been ascertained ; but sooner or later 

 they escape through the opening in it, and seeking a healthy part of the leaf work 



