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Published online by Cambridge University Press: 31 May 2012
Field studies on adelgids and other small non-motile insects living on the bark of trees are often hampered by insufficient magnification and poor light when a hand lens is used. We have tested various commercial illuminated magnifiers but have found that they are either of too low magnification or have too shallow a depth of field.
1 Contribution No. 580, Forest Biology Division, Research Branch, Department of Agriculture, Ottawa, Canada.
2 Part of a joint project of Forest Biology Division, Fredericton, N.B. and Department of Lands and Mines of New Brnnswick, financed in part by funds from the Provincial Department.