1916 ENTOMOLOGICAL SOCIETY. 163 



LEAF-ROLLEKS ATTACKING APPLES. 



L. Caesar, Ontario Agricultural College, Guelph. 



Oil the discovery last year that in at least two well-cared-for commercial 

 orchards much loss had been done hy the Fruit-tree Leaf-roller* [Toririx {Caco'cia) 

 argyrospila], which has the last few years become a very troublesome pest in 

 many parts of the United States, it seemed to me wise to study the habits and 

 life-history of this insect in Ontario so that I might be in a position from actual 

 experience to advise as to the best methods of control in case the insect should 

 increase in numbers and attack more orchards. In this and other investigation 

 work I had the assistance of my colleague, Mr. G. J. Spencer, for a few weeks, and 

 of Mr. H. G. Crawford, a recent graduate, for the whole season. The investiga- 

 tions were conducted chiefly in the large apple orchard of Mr. Jas. E. Johnson, 

 Simeoe, Norfolk County. 



Species of Leap-rollers Found in the Orchard. 



We expected to find two species of Leaf-rollers \Tortn.r (Caarcia) argijros- 

 pila] and the Ohlique-banded Leaf -roller [Tortrix (Cacwcia) rosaceana]. I knew, 

 however, from the large number of unidentified egg masses on the trees that there 

 was another insect present, but what it was I had no idea. Later on we found that 

 it too, was a leaf -roller, which proved to be Tortrix (Caccecia) semiferana, the 

 Box-Elder (Manitoba Maple) Leaf -roller. We thus had three species working side 

 by side. 



A very peculiar circumstance in connection with our work was that though 

 there were about 60 acres of large apple trees in one solid block, the three most 

 important pests studied, the Fruit-tree Leaf-roller, the Box-Elder Leaf-roller and 

 the Capsid {Neurocolpus nuhilus) were all found together towards the centre of 

 this orchard on a block of Spy trees of 6 to 10 acres in extent. Bordering rows of 

 Baldwin trees were also attacked but those some distance removed, as also distant 

 Spy and Greening trees, were very little injured. The explanation of this localiza- 

 tion of insects is hard to discover. This part of the orchard had been in sod 

 longer than the other parts but that scarcely seems sufficient explanation. Prof. 

 Gillette has remarked upon the tendency of the Box-Elder Leaf-roller to appear 

 at the same time and in the same neighborhood, but not on the same kinds of 

 trees as the Fruit-tree Leaf-roller. It is well known that the latter very com- 

 monly centres itself in one locality injuring perhaps a single orchard severely and 

 scarcely attacking at all another a few rods away. 



Relative Abundance of Each Species. 



Though the egg masses of semiferana were almost as abundant as those of 

 argyrospila the larvte of the latter were many times more numerous, at any rate 

 towards the end of the season. This may have been due to the former species 

 being less immune to poisonous sprays (Lugger of "Minnesota reported that Paris 

 green controlled this species) or to some other unknown cause. Jiosaceana was 

 not nearly so abundant even as semiferana. About nine-tenths of the total injury 

 was done by argyrospila. 



_„ _ ^ _^ '* 



*Mr. Aueust Bupck states that the generic name " Arohlps '* has been dropped and 

 " Cacoecia " is tentativrly retained as a subdivision of Tortrix. 



