The Canadian Horticultun^ 



Floral Edition 



Vol. XXXIX 



PETEHBORO. FEBRUARY, 1916 



i\(). 2 



The Fruit-Tree Leaf-Roller 



Professor L. Caesar, Provincial Entomologist, Guelph, Ont. 



THERE are two moderately com- 

 mon leaf-rollers that attack fruit 

 trees, especially apple and pear 

 trees, in Ontario. One of these is known 

 as the Oblique-banded Leaf-roller from 



-Moth of !iif J- rui! -t I ft' Lt'af-roller: the larger 



one i.s a female, the .smaller a male. 



(Both natural size.) 



two broad bands that run obliquely 

 cross each of the front wings of the 

 dult moth, and the other the Fruit- 

 tree Leaf-roller. The former of these 

 insects, though found in almost every 

 orchard, has not to mj' own personal 

 knowledge ever caused any appreciable 

 amount of damage. The same has been 

 true of the latter species until abovit 

 three years ago. Up to that time it 

 had evidently been kept in check by 

 parasites, diseases or other factors, but 

 for some unknown reason these con- 

 trolling forces have of late become 

 weakened so that this insect is now one 

 of the most destructive fruit pests and 

 one of the most difficult to combat. 



This is not a new pest. It occurs 

 from one end of the province to the 

 other, but fortunately up to the present 

 has, so far as the writer can tell, been 

 very abundant, and, therefore, very de- 



structive in only three orchards. One 

 of these is situated near Trenton, an- 

 other near Hamilton, and the third 

 near Simcoe. In the first of these ap- 

 proximately 50% of the fruit during 

 the last two years has been either de- 

 stroj'ed or rendered culls. In the Ham- 

 ilton orchard the loss has not been 

 nearly so great, Math the exception of a 

 few trees which suffered severely. At 

 Siracoe from 40 to 50% of the apples, 

 as nearly as one can judge, were in- 

 jured in the infested part, about 10 

 acres, of a large 60 acre block of apples. 



A peculiarity of the insect is its habit 

 of centering its attack upon a single 

 orchard and scarcely doing any dam- 

 age to neighboring orchards. Some- 

 times it will, as in the case of the Sim- 

 coe orchard, attack severely not the 

 whole orchard, but only a certain por- 

 tion of it. From this peculiarity one 

 feels hopeful that the great mass of the 

 orchards in the province may escape 

 severe attack even though a consider- 

 able number should become badly in- 

 fested. 



Ontario is not the only province or 

 state troubled with this insect. During 

 the last few years it has become a 

 source of worry to fruit-growers in 

 New York and several other states. It 



has been troublesome for many years in 

 Colorado, but is gradually becoming of 

 less importance there. I feel sure that 

 since it is not a recently imported pest 

 that in Ontario the forces which have 

 kept it in check in the past will in a 

 few years again gain the upper hand 

 and reduce it to a position of insignifi- 

 cance. In the meantime it is well to 

 know something about its life-history, 

 habits and means of control. 



Description of Adult and Larva. 



The adult is a small moth about half 

 an inch long when the wings are closed, 

 but with a wing expanse of nearly an 

 inch when these are stretched out. The 

 upper wings are a rusty brown, with 

 several silvery white markings, the hind 

 wings are a light ashy brown without 

 any markings. The larva, when full 

 grown, is a somewhat slender caterpil- 

 lar nearly an inch long, and of a pale, 

 yellowish green color with a black 

 head. They are usually to be found 

 concealed in a leaf loosely rolled up. 

 When disturbed they quickly wriggle 

 out of the leaf, and drop down on a 

 silken thread. When danger is past 

 they crawl up by this thread to the 

 tree again. 



The Oblique-banded Leaf-roller 

 larva looks very much like this one, and 



Kbk clu.ster.s of Fruit-tree Leaf-roller on apple twigs; the whitish ones to the right have 

 hatched, the others are unhatched. (Natural size.) 



