28 



counties of Ontario to cause the defoliation of entire orchards, and 

 conditions favour its further increase, A description of the various 

 stages is given. Both adults and pupae apparently hibernate, the 

 former in such shelters as thatch, and the latter in cocoons attached 

 to the leaves. In England two and probably three generations in 

 a year are recorded and, while there is considerable variation in 

 development towards the end of the season in America, the life-history 

 is probably similar to that in Europe. Eggs are deposited probably 

 when the leaves are partly developed, the caterpillars feeding on the 

 upper leaf-surface, skeletonising the leaves while working under a 

 slight web, the margins of the leaves sometimes being webbed down. 

 This injury probably continues for a month or six weeks. While 

 apple is apparently the preferred food, pear, hawthorn, mountain ash, 

 birch and possibly willow are attacked. It is hoped that some para- 

 sites of H, joariana have become established with the host ; a few 

 individuals of Diodes obliteratus, Cress., have already been reared 

 from American , material. Thorough and timely spraying with lead 

 arsenate on all trees upon which the pest can subsist in infested areas 

 would undoubtedly prevent material damage from the insect, 



Ross (W. A.). The Black Cherry Aphis. — 48th Ann. Rept. Entotn. Soc. 

 Ontario for 1917, Toronto, 1918, pp. 59-68. [Received 16th 

 November 1918.] 



This paper gives an account of Myzns cerasi, F. (black cherry aphis), 

 studied in the Niagara district, where from 6 to 14 generations occur 

 annually. The information amplifies that already given elsewhere [see 

 this Review, Ser. A, vi, pp, 103 and 121]. 



Insect enemies of M. cerasi include the CoccineUids, Adalia bipunc- 

 tata, L,, Coccinelh novemnotata, Hbst., C. transversoguttata, ¥., 

 C. trifasciata, L., C. sanguinea, L., Anatis quinquedecim.punctata, 

 Oliv., Hippodamia tredecimpufictuta, L., and Scymnus collaHs ; the 

 Syrphids, Syrphus americanus, Wied., S. ribesii, L., and Allograpta 

 obliqua, Say ; the Cecidomyiid, Aphidoletes meridionalis. Felt ; 

 Chrysopa sp. and an undetermined Acarid. Weather is one of 

 the greatest factors influencing the numbers of M. cerasi ; heavy 

 showers wash many Aphids from the plants, and droughts, early 

 frosts and wind storms all destroy large numbers, 



Caesar (L.). A Further Report on the Value of Dusting versus 

 Spraying to control Fruit Tree Insects and Fungus Diseases. — 

 48th Ann. Rept. Entom. Soc. Ontario for 1917, Toronto, 1918, 

 pp, 79-85, [Received 16th November 1918.] 



A series of experiments is here recorded similar to those carried 

 out in the previous year with dust sprays as compared with liquids 

 [see this Review, Ser. A, v, p. 549]. As regards cost, dust is considered 

 on the whole cheaper if carefully used. Various tests on apple trees 

 are described, the foliage on all dusted trees being nearly perfect, 

 though that on sprayed trees was almost equally good. As regards 

 the control of codhng moth [Cydia pomonella], there was little or no 

 difference in the efiicacy of the two methods. Trees dusted with 

 sodium sulphide mixed with talc for the control of San Jose scale 



