Ground surveys or samples are used to obtain more accurate estimates of the numbers of insects present for use in determining the trend index and/or the abundance of natural enemies.

EXAMPLES

1. Bark beetle killed trees are sometimes counted on the ground to verify aerial photography (Slide). In addition, populations of insects may be sampled by climbing or felling trees and removing bark samples for later analysis in the laboratory (Slide). X-rays are sometimes employed to count insects in or under the bark. For more information, check the Virginia Tech site by clicking here.
2. Gypsy moth populations are frequently sampled by counting egg masses on tree trunks and branches (Slide), sometimes using sequential sampling techniques (Slide). In addition pheromone traps are employed for monitoring the spread of gypsy moths throughout the United States (Slide).
3. Spruce budworm and Douglas-fir tussock moth populations are also sampled by counting egg masses on the foliage (Slide), or larvae may be counted by clipping or beating the foliage (Slide). Pheromone traps are also employed to monitor annual population fluctuations (Slide).

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