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The economic importance of the Order Trichoptera is confined almost entirely to the immature stages. The bulk of the literature on these insects has in the past dealt mainly with the adult forms. According to Imms (1930) about 1,600 species of the order are known. Betten (1934) in his recent monograph lists 568 species for North America of which number he believes about 55 have had the immature stages described.
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W. A. Elkins (1936) studied this question.
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