Conservation Biology Research Grants Program Nongame Wildlife Program Division of Ecological Services Minnesota Department of Natural Resources THE CADDISFLIES (INSECTA: TRICHOPTERA) OF THE LAKE ITASCA REGION, MINNESOTA, AND A PRELIMINARY ASSESSMENT OF THE CONSERVATION STATUS OF MINNESOTA TRICHOPTERA A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY MARGOT PECK MONSON IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER MASTER OF SCIENCE SEPTEMBER 1994 1 © Margot Peck Monson 1994 2 ACKNOWLEDGMENTS I would like to express my sincere gratitude to my major advisor, Dr. Ralph Holzenthal, for taking me on as his student and for his time, effort, and patient guidance in helping me pursue this project. I also wish to thank Dr. Roger Moon for his helpful counsel and encouragement, as well as the other members of my examination committee, Dr. William Miller and Dr. Francesca Cuthbert, for their support. I am grateful to Dr. O. J. Flint, Dr. Steve Harris, Dr. David Etnier, and the Illinois Natural History Survey for their assistance in making specimens available and for verification of some determinations. Dr. Etnier was also most generous in making several donations to the University of Minnesota Insect Collection. I am thankful for the partial funding for this project, contributed by the Nongame Wildlife Program of the Minnesota Department of Natural Resources and the Minnesota Chapter of The Nature Conservancy. The helpfulness of Dr. Phil Clausen, Curator of the University of Minnesota Insect Collection, was most appreciated (as was his willingness to answer my many questions). The friendship and good humor extended by my colleagues in the lab, Roger, Atilano, Jolanda, Sonia, John, and Marc, as well as Sue, Paul, Sujaya, and Diann will be fondly remembered. My friends Dave, Linda, Bill and Martha, were helpful from the first days of my study and the support of Ann and Ginner in the field was invaluable. Without the love and constant encouragement from my husband, Bjorn, and children, Amy and Bjorn, I would not have been able to complete this project. To them I will always be deeply grateful. i TABLE OF CONTENTS ACKNOWLEDGMENTS .............................................................................................................................. i TABLE OF CONTENTS............................................................................................................................... ii LIST OF TABLES........................................................................................................................................ iv LIST OF FIGURES ........................................................................................................................................v ABSTRACT....................................................................................................................................................1 PART I INTRODUCTION ..........................................................................................................................................3 Trichoptera.........................................................................................................................................7 Morphology .......................................................................................................................................7 Biology ..............................................................................................................................................8 Case and Retreat-making Behavior...................................................................................................9 Trophic Relations.............................................................................................................................13 Distribution ......................................................................................................................................16 MATERIALS AND METHODS..................................................................................................................17 Study Area.......................................................................................................................................17 Collection Sites................................................................................................................................17 Collection Techniques and Equipment ............................................................................................20 Species Determinations and Depositions.........................................................................................24 Diversity and Similarity Indices ......................................................................................................26 RESULTS .....................................................................................................................................................28 Annotated Species List ....................................................................................................................28 Species Richness and Relative Abundance......................................................................................63 Seasonal Distribution.......................................................................................................................77 ii DISCUSSION...............................................................................................................................................87 SUMMARY AND CONCLUSIONS ...........................................................................................................98 LITERATURE CITED ...............................................................................................................................100 PART II A NEW SPECIES AND NEW RECORDS OF OXYETHIRA (TRICHOPTERA:HYDROPTILIDAE) FROM MINNESOTA.................................................................................................................................112 ABSTRACT................................................................................................................................................113 INTRODUCTION ......................................................................................................................................113 METHODS .................................................................................................................................................113 DISCUSSION.............................................................................................................................................116 ACKNOWLEDGEMENTS........................................................................................................................117 LITERATURE CITED ...............................................................................................................................117 PART III A PRELIMINARY ASSESSMENT OF THE CONSERVATION STATUS OF MINNESOTA TRICHOPTERA.........................................................................................................................................119 LITERATURE CITED ...............................................................................................................................135 iii LIST OF TABLES PART I Table 1. All caddisfly species and their abundances in collections from four sites in Minnesota during 1988 and 1989.................................................................................29 Table 2. Species richness, diversity, and evenness.......................................................................................64 Table 3. The 15 most abundant species collected at each site ......................................................................70 Table 4. Ratios of females to males for those species most abundant and collected in 1988 and 1989 at each creek site, and from Beaver Lake.....................................................................................................................................75 Table 5. Similarity of caddisfly fauna between sites based on Sorensen’s Coefficient of similarity...................................................................................................................76 Table 6. Seasonal distribution of caddisfly species collected from the Itasca region of Minnesota, 1988 & 1989........................................................................................78 Table 7. A comparison of caddisfly species richness at regional and Local scales......................................................................................................................................88 PART III Table 1. Annotated checklist of the Trichoptera of Minnesota...................................................................123 iv LIST OF FIGURES PART I Fig. 1. Phylogeny of the Trichoptera ...........................................................................................................11 Fig. 2. Collection sites for Trichoptera in the Lake Itasca region in northern Minnesota.....................................................................................................................18 Fig. 3. Collection sites. A. Nicollet Creek; B. Beaver Lake .......................................................................19 Fig. 4. Collection sites. A. Sucker Creek; B. LaSalle Creek.......................................................................21 Fig. 5. A. Light trap; B. Malaise trap. .........................................................................................................23