1915 ENTOMOLOGICAL SOCIETY. 105 



How Long the Mite Has Been in Ontario? 



The chief means of distribution is doubtless on nursery stock and by birds and 

 flying insects. These agencies may soon distribute a pest over a great deal of ter- 

 ritory, but from the fact that the Blister Mite {Eriophyes pyri), though known in 

 the province for many years and distributed in the same manner, has not yet reached 

 nearly all our orchards, it seems clear from the wide distribution of this mite that 

 it^is no recent importation, but has been here for many years and has hitherto been 

 mistaken for the Red Spider, T. bimacidatus. 



Life History So Far As Observed. 



The winter is spent in the egg stage. The eggs are small, globular and blood 

 I'cd, and are deposited in great abundance in the axils of branches and twigs 

 on infested trees. Many eggs were found also in the calyx and stem ends of apples. 

 Egg laying was observed this year (1914) on October 7th, but many had been laid 

 before this date. Not a few adults were still present at the above date on the leaves. 

 Until last year (1913) the writer had supposed that these eggs had all been de- 

 posited hy Bryobia pratensis, but having actually seen T. pilosus laying the eggs, 

 and noticed that infested trees regularly had these eggs whereas uninfested ones 

 were almost without them, he is convinced that so far as Ontario is concerned the 

 most of thase eggs are laid by this new species, and not by Bryohia pratensis. 



It may be worth mentioning that as soon as a female of T. pilosus deposited 

 an ftgg she spent approximately a minute in fastening a few silken threads to or 

 or over it, apparently with the object of holding it in place. T. mytilas'pidis has, 

 I bolieve, the same method of attaching her eggs. 



At Guelph this year the eggs hatched about the time the leaves on the European 

 plums were expanding viz. about May 15th. The exact date was not determined, 

 but it was some time after the buds had burst. On May 23 little, immature, red 

 mites were found and brought into the laboratory. By May 27th these had become 

 adults and were then easily identified. By May 28 a few eggs were laid on the 

 leaves of a well sheltered European plum tree in the Avriter s garden. The Avinter 

 eggs had probably hatched earlier on this tree than in the average orchard. 



No study was made of the length of the incubation period of the eggs, nor of 

 the larval stages or number of generations a year. It is evident, however, from the 

 rapid rate of increase that there are many generations and breeding continues right 

 up to the cold weather in autumn. The severe frosts then evidently kill off all the 

 adults. 



Control. 



A tree badly infested in the early part of t<his summer was seen to be almost 

 free from mites in August. It was also noticed that in the Niagara district the mites 

 were not nearly so numerous as last year, whereas in Norfolk County they were 

 still very abundant in October. It is, therefore, .apparenit that there is some natural 

 means of control that is very helpful, but what this is was not discovered. A year 

 ago when the mites were very ahundant on an isolated European plum tree the writer 

 had this thoroughly sprayed with the ordinary summer strength of lime-sulphur, 

 the spray being applied to the under surface of the leaves. The result was very satis- 

 factory. It is very probable, therefore, that where orchards are badly infested the 

 mites can be controlled by using lime-sulphur instead of bordeavix mixture for the 



8 e.s. 



