distribution of specific insects and diseases is contained in the Annual Report of 

 the Forest Insect and Disease Survey. 



The spruce budworm infestation in northwestern Ontario declined substan- 

 tially again in 1963 to a comparatively small area of light infestation, amounting to 

 about 3,500 square miles, in the southeast corner of the Fort Frances District and 

 the adjacent southwest corner of the Port Arthur District. This represents the 

 lowest level of budworm activity in northern Ontario in more than 25 years. 

 Nevertheless, budworm larvae were collected at several spot locations across 

 northern Ontario through intensive sampling. 



In southern Ontario there were small pockets of light to medium budworm 

 infestation in the Lake Erie, Lake Huron, Lake Simcoe and Tweed Districts. The 

 infestation which has persisted in a 40-year-old white spruce plantation in the 

 Uxbridge Forest for over 10 years, increased from medium to heavy in 1963. 

 Control operations have been withheld from this plantation because of the unusual 

 opportunity to study budworm behaviour and tree reaction in an isolated, pure 

 stand of young white spruce. 



The forest tent caterpillar outbreak developed less extensively than expected 

 during 1963 because of adverse weather conditions. Despite this set-back, it 

 expanded and defoliated aspen stands over an area of about 19,000 square miles 

 in northwestern Ontario, including all of the Kenora District and adjacent portions 

 of the Sioux Lookout and Fort Frances Districts. In eastern Ontario the outbreak 

 areas remained scattered, totalling 700 square miles, in areas west of Sudbury, 

 west of Lake Nipissing, surrounding the Muskoka Lakes, and at several localities 

 in the eastern part of the Pembroke District. 



Larch sawfly populations across northern Ontario caused insignificant damage 

 during 1963 and were at the lowest general level in 20 years. Populations of the 

 larch sawfly across southern Ontario, although reduced somewhat, were still quite 

 noticeable, especially in older plantations of European and Japanese larch in the 

 Lake Simcoe and Lake Erie Districts. 



The introduced European pine sawfly, which defoliates Scots and red pine 

 plantations, extended its range eastward in southern Ontario, so that the eastern 

 boundary is now a line from Midland south to Barrie and Newmarket, and then 

 curving eastward along the south shore of Lake Scugog, and south to Newcastle. 

 This represents a modest easterly extension during 1963 of about seven miles for 

 the area south of Barrie. The spot infestations farther east near Vernon ville and 

 at Belleville also increased in area. 



The eastern tent caterpillar, which is conspicuous by the tent it makes on 

 wild cherry and apple trees principally along roadsides, remained about the same 

 or showed a downward trend in numbers during 1963 in southern Ontario. How- 

 ever, in the southern part of the North Bay District there was a general increase. 



The birch skeletonizer causes late summer browning of white-birch leaves 

 which is quite spectacular in appearance but has almost no impact on the trees. 

 Across central and southern Ontario, populations of this insect had been high 

 since 1959, but declined in 1963. However, in northern Ontario the insect had a 

 substantial upswing in numbers in parts of the Sioux Lookout District, in a wide 

 band extending south from Lake Nipigon to Lake Superior and along the east 

 side of Lake Nipigon, and in parts of the White River, Gogama, Cochrane, Swastika 

 and North Bay Districts. 



The distribution of Dutch elm disease in Ontario remained virtually unchanged 

 during 1963, occurring throughout southern Ontario as far north as North Bay. 

 However, within this area there was a notable increase in elm mortality in some 

 localities. 



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