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This study has been an intermittent effort since 1975 and would have expired somewhere along the way had it not been for the generous support of the following organizations: Morgan Library, Colorado State University, Fort Collins, for help with references and interlibrary loans; U.S. Fish and Wildlife Service Denver Wildlife Research Center and Columbia National Fisheries Research Laboratory—Denver, for literature search and field reports.

Herbarium records, information, advice, or field support were supplied by

• Beneficial Insect Laboratory,
  U.S. Department of Agriculture,
  Beltsville, Maryland -- J. Coulson.
• Biologische Station, 'Rieselfelder Munster',
  Federal Republic of Germany -- M. Harengerd.
• California Department of Food and Agriculture,
  Sacramento -- D. Barbe.
• California Native Plant Society,
  San Francisco -- E. McClintock.
• Commonwealth Institute for Biological Control,
  Delemont, Switzerland -- D. Schroeder.
• Naturhistorisches Museum,
  Wien, Austria -- P. Prokop.
• University of Nebraska-Lincoln -- R. Kaul.
• Vildtbiologish Station,
  Kalø, Denmark -- H. Strandgaard.

We are also grateful to more than 75 persons for advice, help, or information, especially L. Andres, S. Batra, F. Bellrose, P. Boldt, T. Bookhout, S. Brezinski, H. Brumsted, R. Clark, G. Cole, C. Dane, L. Davis, N. Dawe, V. Dewey, J. Elder, G. Gavutis, F. Golet, M. Hall, C. Hardy, B. Harper, F. Helmer, T. Jackson, R. Jones, H. Kano, E. Kiviat, E. Kivisalu, R. Malecki, P. Mann, K. Menzel, H. Miller, J. Morse, E. Moses, J. Mullan, A. Nice, T. Nigus, N. Norton, A. Notestein, H. O'Connor, M. Olson, M. Phillips, B. Popelka, T. Rawinski, P. Reed, M. Richmond, C. Robbins, J. Seubert, R. Sleeper, R. Streeter, S. Taylor, D. Thompson, D. B. Thompson (graphics), D. Tiller, L. Van Druff, D. Wade, W. Willen, S. Williams, E. Woehler, and J. Zimmerman.

Finally, we thank the New York Cooperative Wildlife Research Unit for providing the funds to publish this report.