Bulletin OF THB Illinois State Laboratory ov Natural History Urbana, Illinois, U. S. A. STEPHEN A. FORBES, Ph.D., L.L.D., Director Vol. XI. September, 1915 Article II. AN ECOLOGICAL, STUDY OF PRAIRIE AND FOREST INVERTEBRATES BY Charles C. Adams, Ph.D. — ERRATA AND ADDENDA. Page 50, second column, line 13 from bottom, for Danais arcMppus read Anosia plexippns ; line S from bottom, for melliflca read mellifera. Page 51, line 11 from bottom, for Danais read Anosia. Page 159, at right of diagram, for Bracon agrilli read Bracon agrili. Page 289, second column, last line but one, for Scalops real Scalopus. Page 294, line 3, for c.atesheana read catesiiana. Pages 327 and 330, line 12, for oreus read oreas. Page 347, line 4, for Cecidomyidae road Cecidomyiidae. Page 356, line 7, for Anthomyidse read Anthomyiidae. Page 368, line 18, dele second word. Page 373, after line 10 insert as follows: 53a, suipruinosa Casey, 1884, p. 38. Page 375, after suXimucula Le Conte, 48, insert subpruinosa Casey, 53a. Page 377, after line 7, insert as follows: 1884. Casey, Thomas L. Contributions to the Descriptive and Systematic Coleopterology of North America. Part I. Page 379, line 11 from bottom, for sen.iu lata read sensu lato. Page 382, line 12, for VII read VIII. Page 408, line 2, for the next article in read Article VIII of. Page 410, line 6 from bottom, for = 4 read '11. Page 412, line 7, for 31 read 30. Page 421, line 17 from bottom, insert it before grows. , CONTENTS Pagh Introductory 33 General description of the region and location of the ecological stations 35 I. General description of the region 35 II. The ecological stations 38 Description of the prairie habitats and animals 40-56 I. Prairie area north of Charleston, Station 1 40 1. Colony of swamp grasses (Spartina and Elym-us), Station I, a.. 41 2. Colony of wild rye, Elymus virginicus submuticus, Station I, c. 43 3. Wet area of swamp milkweed (Asclepias incarnata) , Station I, d 44 4. Cone-flower and rosin-weed colony, Station I, e 48 5. Colony of blue stem (Andropogon) and drop-seed ( Sporoiulus ) bordered by swamp milkweed, Station I, f/ 49 6. Supplementary collections from Station 1 52 II. Prairie area near Loxa, Illinois, Station II 52 III. Prairie area east of Charleston, Station III 55 Description of the forest habitats and animals 56-66 1. The Bates woods. Station IV 56 2. The upland oak-hickory forest, Station IV, a 57 3. Embarras valley and ravine slopes, forested by the oak-hickory association. Station IV, ft 59 4. Lowland or "second bottom," red oak-elm-sugar maple wood- land association. Station IV, c 62 5. Supplementary collections from the Bates woods. Station IV. 65 6. Small temporary stream in the south ravine, Station IV, d 65 General characteristics of the gross environment 66-102 1. Topography and soils of the State 66 2. Climatic conditions 67 3. Climatic centers of influence 69 4. Eelative humidity and evaporating power of the air 71 5. Temperature relations in the open and in forests 83 6. Soil moisture and its relation to vegetation 86 7. Ventilation of land haliitats 88 8. The tree trunk as a habitat 91 9. Prairie and forest vegetation and animal life 91 10. Sources and role of water used by prairie and forest animals. ... 98 Animal associations of the prairie and the forest 102-158 I. Introduction 102 II. The prairie association 103 1. Swamp prairie association 103 2. The Cottonwood community 105 3. Swamp-grass association 107 4. Low prairie association 108 5. Upland prairie association 109 6. The Solidago community 109 7. Dry prairie grass association HI 8. A milkweed community 112 III. Relation of prairie animals to their environment 113 1. The black soil prairie community 114 2. The prairie vegetation community 117 4. Interrelations within the prairie association 119 Page IV. The forest associations 122 1. Introduction 122 2. Dry upland ( Quercus and Carya) forest association 124 3. Artificial glade community in lowland forest 125 4. Humid lowland (hard maple and red oak) forest association. 126 5. Animal association of a temporary stream 127 V. Relation of the deciduous forest invertebrates to their environment. 128 1. Forest soil community 129 2. The forest fungus community. 135 3. The forest undergrowth community 138 4. The forest crown community 139 5. Tlie tree-trunk community 142 6. The decaying wood community 148 7. Interrelations within the forest association 157 Ecologically annotated list: — I. Prairie invertebrates 158-201 II. Forest invertebrates 201-238 BibUography 239-264 Article II.—An Ecological Study of Prairie and Forest Inverte- brates. By Charles C. Adams, Ph.D. Introductory In four generations a true wilderness has been transformed into the present prosperous State of IlHnois. This transformation has been so complete that in many parts of the state nearly all of the plant and animal life of the original prairie and forest has been completely ex- terminated. Between the degree of change which has taken place in any given area and the suitability of that area for agriculture there has been an almost direct relation. Fortunately, however, for the preser- vation of prairie and forest animals, the state is not homogeneous, some areas being too hilly, rocky, or sandy for prosperous agriculture. The character and mode of transformation which has taken place in the past is instructive in several particulars because it serves to guide our anticipations as to the future of our fauna. The forested southern part of the state (see frontispiece) was first invaded by trap- pers and hunters, who began the extermination of the larger animals. These invaders were in turn followed by others who, with the round of the season, were hunters or farmers, and continued this exterminat- ing process, particularly in the clearings, which began to replace the forest. These pioneers, men of little wealth, possessed a combination of mental and economic habits which was the result of life in a for- ested country, and naturally they settled in those places most like their former homes—within the forest or near the forest margin. From these settlements they looked out upon the prairies as vast wastes to be dreaded and avoided. As a result of this attitude toward the prai- ries, it required some time, even a new generation, some economic pressure, and a change of habits before the prairies were settled. Mean- while the northern part of the state was yet a wilderness ; but through the influence of the Great Lakes, as a route of communication with the populous East, a rapid invasion of settlers set in from that direc- tion. Though these settlers also came from a wooded country, they were more wealthy, settled upon a very fertile soil which was favorably located with regard to eastward communication, and they therefore progressed more rapidly than the less favored, more isolated southern invaders on the poorer soil ; consequently they spread from the forest . 34 to the prairie more rapidly than did the settlers in the South. There thus developed two active centers of influence, each of which trans- formed the primeval conditions in the same manner and in the same direction toward an environment suitable for man. The forests and the upland prairie were first changed. Then the fertile wet prairie was drained, so that today it has largely become either the hilly and rocky areas that survive as forests or the low periodically flooded tracts, and the undesiral^le sand areas which simi- larly preserve patches of sand prairie. All the changes are more rapid and complete upon fertile soil than upon the poorer soils in the southern part of the state. Such considerations as these will aid one in estimating the probable rate of future changes in different parts of the state, and will serve to show in what parts there is urgent need of local studies if ecological records are to be made before extinction of some forms is complete. A study has been made with the idea of reporting upon represen- tative patches of prairie and forest in a manner which would aid others in making similar local studies, and would at the same time preserve some records of the present condition of the prairie and forest. When this work was planned, we had no general or comprehensive discussion of the conditions of life upon the prairie and in the forest. For this reason a general summary of these conditions and a sketch of the gen- eral principles involved are given, so that the reader may gain some conception of the relation of the local problems to those of a broader and more general character. A section for this report was prepared giving general directions for making such local studies, but later it was decided to publish this separately, in somewhat extended form, asi a "Guide to the Study of Animal Ecology."* This volume should be regarded as intimateh^ re- lated to this paper, and this report should at the same time be consid- ered as a concrete example of the procedure suggested in that "Guide" for ecological surveys. It will be observed that the study of the Charleston area here referred to has been conducted in much the same way as was my cooperative study of Isle Royale, Lake Superior, en- titled "An Ecological Survey of Isle Royale, Lake Superior" ('09), although certain aspects have been elaborated here which, for lack of time, were not treated there. The time devoted to the study of the Charleston area was also limited, but in the preparation of the report upon it use has been made of many years' experience and a general knowledge of the prairie and forest.