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

2012 Population Monitoring - Results and Predictions for 2013
Western spruce budworm egg mass sampling was conducted at 620 sites in the Cariboo, Thompson Okanagan and
Kootenay Boundary Regions. Sampling sites were selected based upon 2012 defoliation, recent past defoliation,
stand hazard rating, historic outbreak range, stand structure and composition. The average number of egg masses
per 10 m 2 foliage was higher in the Thompson Okanagan than in the Cariboo and Kootenay Boundary Regions,
at 70.7, 29.9, and 23.3, respectively. Over 50% percent of the sites sampled in the Thompson Okanagan Region
predict moderate or severe defoliation for 2013, compared to just 13% of the sites in the Cariboo. Over 90%
of surveyed sites in the Kootenay Boundary Region had low egg mass numbers, predicting light defoliation in
2013 (Table 9).
Table 10 summarizes the results of egg mass sampling within more localized geographic areas in the Kootenay
Boundary and Thompson Okanagan Regions, identifying the location of potentially significant budworm populations.
In the Kootenay Boundary, the highest populations were found at sites near Grand Forks and east of Rock
Creek. This Region plans to treat 5,000 hectares with B.t.k. in 2013.
In the Thompson Okanagan Region, areas sampled from south of Kamloops through Merritt and down to the
Coldwater River indicated significant budworm populations (Table 10). The Douglas-fir forests surrounding
Seton Lake, Downton Lake, Marshall Lake and the Gold Bridge area will see another year of high budworm.
This area was defoliated in 2011-12 and egg mass counts remain high (Table 10). A public meeting was held in
Gold Bridge on September 3 rd , 2012, to inform Gun Lake area residents about budworm and possible control
options. Approximately 6,500 hectares in this area are proposed for treatment with B.t.k. in 2013. An additional
26,000 hectares in the Cascades District are proposed for spraying, as well as 17,500 hectares south and west of
Kamloops. In total, the Thompson Okanagan Region is planning to treat 45,000 hectares in 2013.
The Cariboo Region has approximately 25,000 hectares scheduled for spraying with B.t.k. next year.
Table 9. Results of fall 2012 western spruce budworm egg mass sampling in southern B.C.
Percent of sites in each defoliation category Number Avg. # egg masses
District Nil Light Moderate Severe of sites per 10m 2 foliage
Cariboo Region
100 Mile House 6% 82% 11% 1% 85 31.2
Central Cariboo 1% 85% 13% 1% 107 33.1
Chilcotin 36% 50% 14% 0 28 21.5
Quesnel 18% 82% 0 0 11 10.5
Region Average 8% 80% 12% 1% 231 29.9
Thompson Okanagan Region
Cascades 3% 25% 51% 21% 115 92.0
Kamloops 5% 43% 37% 14% 92 75.9
Okanagan Shuswap 5% 65% 30% 0 84 35.7
Region Average 4% 43% 41% 13% 291 70.7
Kootenay Boundary Region
Boundary 2% 91% 8% 0 64 22.4
Revelstoke 0 100% 0 0 6 13.7
Rocky Mountain 0 89% 11% 0 28 26.0
Region Average 1.0% 91% 8% 0 98 23.3
Southern B.C. average 5% 64% 25% 6% 620 37.4
Ministry of Forests, Lands and Natural Resource Operations, Kamloops, B.C.
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