Forest Insect and Disease Survey; Ontario, 1965 - NFIS

C 10
Balsam Shoot-boring Sawfly, Pleroneura borealis Felt
Low population levels of this shoot-boring sawfly occurred in balsam-fir stands
throughout the district (Table 13). These levels conformed with the biennial
occurrence of the insect and higher populations may be expected in 1966.
TABLE 13
Summary of Balsam Shoot-boring Sawfly Larval Counts at Six Points
in the North Bay District from 1962 to 1965
Note Counts were based on the examination of twenty 18"-branch tips, four from
each, of five trees at each point.
Location
Av, d.b.h. of
sample trees
Per cent of new shoots infested
township. in inches 1962 1963 __ 1964 1965
East Ferris 4 17 2 25 2
Calvin 4 13 3 15 6
French
5 25 0 13 1
Hugel 6 12 0 14 4
Sisk 4 27 2 16 1
Gillies Limit 5 5 1 12 3
Larch Sawfly, Pristiphora erichsonii (Htg.)
Since 1961 populations of the larch sawfly have remained at a low level throughout
the district. In 1965 small larch stands were lightly defoliated at several
locations in Loudon and Haddo townships. Scattered colonies were found in most
larch stands examined in the southern and central parts of the district but rarely
in the northern part,
Birch Leaf Miners, Prof enusa thomsoni (Konow)
Heterarthrus nemoratus (Fall.)
From 1962 to 1964 population levels of these lea f miners remained low, due
probably to competition for food resulting from severe infestations of the birch
skeletonizer during that period. With the decline of birch skeletonizer infestations
in 1964 and 1965 population levels of the miners increased appreciably and
mined leaves were found in most white birch stands examined. Pockets of light
infestation were observed in the townships of Joan, Field, Gillies Limit, and
Strathy.
Poplar Leaf Roller, Pseudexentera oregonana Wlshm.
High population levels of this leaf roller were present in poplar stands
throughout the district in 1965. Pockets of severe defoliation occurred at many
locations in the townships of Calvin, Bonfield, East Ferris, West Ferris, and
Widdifield. Moderate defoliation was general in the Field, River Valley, and
Hagar areas interspersed with pockets of severe defoliation. Generally, infestations
were light elsewhere in the district except for isolated pockets of moderate
and severe defoliation in the central and northern sections.