1919 ENTOMOLOGICAL SOCIETY. 23 



INSECTS OF THE SEASON IN ONTARIO. 



"VV. A. Ross, Dominion Entomological Laboratoky, Vineland Station, Ont., 

 AND L. Caesar, Ontario Agricultural College, Guelph. 



Orchard Insects. 



San Jose Scale {Aspidiotus perniciosus). The severe winter of 1917-18 

 destroyed a very high percentage of the scale. Inspectors from all scale districts 

 report less of this insect this year than for many years. In two Woodstock 

 orchards infested for at least the past ten years, it has, so far as the Provincial 

 Inspector could judge, completely disappeared, no live scale being found on 

 fruit or branches in October. 



Green Apple Aphis {Apliis poini). During the summer there was a wide- 

 spread outbreak of the Green Apple Aphis. In most orchards the infestation 

 did not attain serious proportions until about mid-July, and from then on it 

 was somewhat rapidly brought under control by hot, dry weather and by insect 

 enemies, until l)y the second week of August comparatively few aphids were left 

 on the trees. 



In most cases no great damage was caused by the aphis apart from coating 

 the fruit with the sooty honeydew fungus. Fortunately, most of this was washed 

 off Taefore picking time by heavy rains. 



White-marked Tussock Moth {Hemerocampa leucostigma) . In view of 

 the abundance of the tussock moth egg masses on orchard trees last fall, the out- 

 break of this season came as no surprise. Apple and plum orchards throughout 

 the Niagara District and Western Ontario were badly infested and much damage 

 was done to the fruit. 



Fortunately for all concerned, the tussocks were parasitized so heavily by 

 hymenopterous and tachinid parasites that only an insignificant number reached 

 the adult stage. We can safely look forward to next year as a season of com- 

 parative immunity from this pest. 



Pear and Cherry Slug (Caliroa cerasi). During June and July, cherry, 

 pear and plum trees in various parts of the Province were seriously injured by 

 this insect. In many orchards the foliage, particularly of sour cherry trees, was 

 almost wholly destroyed. At picking time much of the fruit on badly infested 

 sour cherry trees was wizened, slug-eaten and unfit for sale. 



A very large percentage of the second generation eggs were destroyed by a 

 minute parasite, Trichogramma minutum Riley.* 



Pear Psylla {Psylla pyricola). This pest was again very abundant in 

 various pear orchards from Burlington to the Niagara River. It is worth while 

 recording here that large numbers of trees which had been seriously injured by 

 pear psylla in preceding seasons succumbed to the low temperatures of last 

 winter. 



Fruit Tree Leaf-roller (Tortrix argyrospila) . This insect has apparently 

 almost completely disappeared east of Toronto, but there are some indications 

 that it may be on the increase in the south-western part of the Province. At 

 Simcoe, it caused considerable loss to Greenings. At-Ancaster, there are a good 

 many egg masses, indicating that in this locality there will likely be considerable 

 injury from the leaf roller next year. 



•Species determined iby Mr. A. B. Gahan, U. S. Bureau of Entomology. 



