here. - Ministry of Forests, Lands and Natural Resource Operations

2012 we S t e r n he M l o c k lo o P e r SP r aY Pr o g r a M Su M M a r Y
Trap catch data and egg sampling results from 2011 indicated that western hemlock looper, Lambdina fiscellaria
lugubrosa, would reach outbreak levels in several locations in the southern interior in 2012. Planning for spray
programs in the Cariboo, Thompson Okanagan and Kootenay Boundary Regions using B.t.k. was initiated. Up
to 7,500 hectares in the Cariboo Region near Quesnel Lake were scheduled, but early summer monitoring indicated
very low larval populations throughout the planned treatment area. Therefore, the Cariboo spray program
was cancelled.
In total 12,797 hectares were treated with Foray 48B (B.t.k.) in 2012 to manage western hemlock looper populations
(Table 11). Treatment rate in all blocks was 2.4 litres per hectare. In the Thompson Okanagan Region, a
total of 4,014 hectares were treated on July 11, 2012, near Serpentine Creek and Mud Lake, in the North Thompson
River area (Table 11). Approximately 5,700 hectares were originally proposed for treatment in this Region,
but a few areas in the upper Shuswap River and near Finn Creek, were deleted due to low larval numbers. In the
Kootenay Boundary Region, 7,967 hectares of high priority mountain caribou habitat in the Lake Revelstoke and
Mica areas were treated on July 6-7, 2012 (Table 11).
Table 11. Thompson Okanagan and Kootenay Boundary Regions western hemlock looper 2012 spray summary
showing by block location the hectares sprayed, litres of Foray 48B (B.t.k.) applied and date sprayed.
Area Treated Litres of Date
Region Location (hectares) B.t.k. applied Sprayed
Thompson Okanagan Serpentine Creek (3 blocks) 1,645 3,948 July 11
Thompson Okanagan Mud Lake (5 blocks) 2,369 5,686 July 11
Kootenay Boundary Yellow Creek (3 blocks) 816 1,958 July 6
Kootenay Boundary Pat Creek (5 blocks) 1,005 2,413 July 7
Kootenay Boundary Bigmouth (10 blocks) 3,612 8,668 July 6
Kootenay Boundary Goldstream (3 blocks) 2,691 6,458 July 7
Kootenay Boundary Downie Creek (3 blocks) 659 1,583 July 7
Total 32 Blocks 12,797 30,713
Spray efficacy sampling for the hemlock looper program was conducted in three areas in the Kootenay Boundary
Region (Table 12). Three 3-tree beatings were done in each spray and control block for each area. Lower
branches of each tree selected (nine trees per site) were beaten onto a 1.5 metre x 1.5 metre tarp (area=2.25 m 2 )
and all larvae in the sample were identified and tallied. At the pre-spray assessment, western hemlock looper
density ranged from 1-2 insects per sample at the Goldstream and Downie treatment sites, up to 28 larvae per
sample at the Mica site (Table 12). The effect of B.t.k. was immediate and significant, with larval mortality over
90% in all spray blocks. Abbott’s corrected percent mortality (comparing treated to control areas) ranged from
73 to 99% (Table 12).
Table 12. Summary of 2012 pre- and post-spray sampling for western hemlock looper in the Kootenay
Boundary Region. The number of larvae per site is based on a nine tree beating sample using a 2.25 m 2
beating sheet. The overall percent morality and Abbott’s corrected mortality (percent) is shown for each site.
Geographic Area and Larval density (# per 2.25 m 2 ) % Mortality
Treatment Type Pre-spray 1st post 2nd post Uncorrected Abbott’s corrected
Downie Creek. - control 10.6 6.7 1.8 83.0
Downie Creek. - B.t.k. 1.7 0.6 0.01 99.4 96.5
Goldstream - control 6.8 6.8 2.1 69.1
Goldstream - B.t.k. 1.2 0.2 0.1 91.7 73.0
Pat Cr-Mica Townsite - control 8.7 9.8 11.8 -35.6
Pat Cr-Mica Townsite - B.t.k. 27.9 1.4 0.2 99.3 99.5
Ministry of Forests, Lands and Natural Resource Operations, Kamloops, B.C.
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