SOME l!OTES on THE ECOLOGY OF PRAIRIE INSECTS BY George O. Hendrickson A Thesis submitted to the Graduate faculty for the Degree o'f w..STER OF SCIElWE l~jor subjeot Entomology Signatures have been redacted for privacy Iowa State College 1926 -2- .Aclrnowledgme~ts The preparation of this thesis would not have been possible without the assistance of many persons. The writer is deeply obligated to Dr. R. H. IDlight, under whose direc- tion the work was done, for his very great assistance in de­ termining most of the Hemiptera. in loans of valuable liter­ ature, in timely suggestions and helpful criticisms in collect­ ing, and mounting insects, in securing the aid of other work­ ers, and in pursuit of the study in general. To Dr. C. J. Drake, for determination of the Tingididae, for loans in literature, and for his sti~ulating interest in the problem, the writer wishes to express true gratitude. Dr. B. B. Fulton, for determination of the Orthoptera. for loans in literature, and for helpful suggestions, is deserving of many thanks. The writer wishes to express his appreciation to Dr. W. H. Wellhouse, who has been very ready with loans in literature and with constructive views that were of much value in the study. To Prof. H. M. Harris many thanks are due for determina­ tion of the Irabidae and Anthocoridae. und for helpful demon­ strations in the technique of field observation. Other speCial­ ists, who have been of invaluable assistance in determining the collection are: Prof. J. E. Guthrie. Iowa state College, in Collembola; l~. Nuthan Banks, Museum of Comparative Zoology, Cambridge, Mass., in Ueuroptera; lrt'. Charles Hoffman, Iowa -3- State College, in Odonata; Prof. J. Douglas Hood, University of Rochester, :U. Y., in Thyso.nopteraj Hr. H. G. Barber, Roselle, 1~. J., in Renlptera.; l!Tr. VIm. T. Davis, Staten Island, ll. Y., in Cicndidae; Prof. D. l!. DeLong, Ohio State University, and Dr. E. D. Ball, Sanford, Florida, in Homopteru; Prof. H. F. Wickham, state University, Iowa City, Iowa, in Coleoptera; Hr. Rodney CeCil, Geneva Agricul. tU1~al Experiment Station, ·Geneva, :U. Y., in Coccinellidaej Dr ...4.nnette F. Braun, CinCinnati, Ohio, Dr. H. G. Dyar, National Museum, Washington, D. C., and Dr. W. T. M. Forbes, Cornell University, Ithaca, N. Y., in Lepidoptera; Prof. J. S. Rlne, Ohio State University, Columbus, Ohio. and Prof. R. J. Reinhard, Texas AgriCUltural Experiment Station, College Station, Texas, in Dipteru; Prof. C. L. Pluke, Uni versi ty of' Vlisconsin, l!adlson, tlis .. , in Syrl)hldue; lass Grace Sandhouse, Messrs. A. B. Gahan, R. A. Cushman, and S. A. Rohwer, national lfuseum, Vlashington, 'D. C., and 1tr. R. L. Vierecl:, Department of Agriculture, ottawa, Canada, in Hymenoptera; and Dr. M. R. Saith, Mississippi Agricultural and }.!echanicnl College, Miss., in Formicidae; Dr. Ado. Hayden, and l~. R. G. Reeves, Iowa stuto College, have aided in the 1dentificution of plants. -4- Introduction The native prairie or Iowa has nearly disappeared. Ex­ cept for railroad right-of-ways, and ungraded roadsides, very few tracts of tillable native prairie can be ~ound. But these few areas may be preserved far many years becau~e of general interest in the native conditions o~ the state. Many insects were native to the prairie. Occasionally, conditions arise which enable or require a native insect species, hereto~ore considered of little or no economic importance, to become an annoying pest of a cultivated crop. Many native harmless species are with difficulty distinguished from the more injurious species of neighboring fields. Hence~ it was thought that a study of insects native to a tract of prairie would be of interest and value to many workers in entomology. The objeots of this study are, chiefly, to determine a list of insects native to a tract of original prairie in Ioua, to make further observations on the habits, food, end life-histories of prairie insects, and to obtain data on the climate seasonally assooiated with these species and the surveyed tract. It is expected that this study may become the basis for continued investigation into the fac­ tors of the relationsh1ps between the insect fauna. and the flora of the original prairie of Io~a. General Description of the Collecting Station The locality chosen for the collecting is a five acre -5- tra.ct of prairie preserve on the fa.rm of Doctor J~da Hayden. The farm is in story County, near the centra1 part of the state. The southeast corner, of the farm is three miles north and one mi1e west of the junotion of Linooln Way and Gra.nd Avenue in the city of ,,\mes. The surveyed tract is one-fourth of a mi1e west and one-fourth of a. mile south of the southeast corner of the farm, and lies toward the northern edge of the terrace over- 100king a va11ey whioh leads eastward toward the Skunk river, about one mile distant. This traot was chosen because it is known to have been original prairie for more than the last fifty years, beoause Doctor A~a Hayden has published several articles on the ecology of the plants of the preserve, and be­ cause it will probably remain a preserve for soientifio inves­ tigation for a number of years. Plant Features of the Station Hayden (1919) has classified this tract in plant ecology as a stipa-Bouteloua Formation in a Prairie PrOVince, and has divided the Formation into Consocies Bouteloua and Consocies sti~. She states that Consooies Bouteloua is located on the hilltops with gravelly loam Boil, and has as "the prinoipal speoies; "Bouteloua curtipendula, Bouteloua hirsuta, Koeleria cristata, Carex pennsylvaniaa, Astragalus oarlocarpus. Comandra -6- umbellatu, Anemone cylindrica, Anemone patens var. Violtgangiana, Agoseris auspidata, Oenothera serrulata, Solida~o speciosu, Liatris oylindrica, Euphorbia corollata, Lithospermum canescens, Li thoSPSt'InUm aJlgustltollum, petalostemum purpureum., Polygala verticillata. "The societies ot the seasonal aspects are: (1) Spring aspect. Anemone patens var. Wolf'gangiana, Comandra umbellata, Agoseris cuspidata. (2) Sumner aspect. Bouteloua aurtipendule., Bouteloua hirsuta, Koeleria. cristata, polygo.la verticillata.. (3) Fall asnect. Bouteloua hirsuta., Bouteloua ourtiRondula., Andropogon furcatus, Liatris cylindrica, hster azureus, Solidago s1>ec10so.." Doctor Hayden located the slopes of the hills with loam to sandy loam soil as the Consocies Stipa, with "the main species: "Brauneria purpurea, Psoralea argop~ylla, stipe. spartea, Sporobolus, CQreopsls palmata, Liatris pycnostachya, Llatris squarrosa, Lespedeza. capltata, DelphinIum. Penard1., Lilium philadelphicrum, Phlox pilosa, Heuchera Americana, Pedicularis canadensis, Viola pedata, Baptisia bracteata, Eryngium yuccae­ :folium, Amorpha canesoens., Gentiana puberula, Solidata0 speciosa, Sol~dago rigida, Petalostemum purpureum, Sisy!inchium angusti­ :folium, HyPoxis hirsuta, Aster sericeus, Aster multiilorus. "Societies: (1) Spring aspect: Viola pedatn,. Pedicularis canadensis, Phlox llilosa, Baptisia bro.ateata, Sisyrinch1um angusti:folium. (2) SUmmer as:peot: Brauneria ;purpurea, Lilium -7- philadelphioum, Amorpha oanescens, HoucherD. Americana, Psora-loao.; arGophylla, Er~ium yuccaefolium, Desmodium illinoense, Lespedeza capi~atat Lespedeza leptostaoh~. (3) Fall aspect: Aster Dn'~tlflorus, Liatrls pycnostach~. Liatris squarrosa. Gentlana ll!*berula, Aster azureus, Aster sericeus. n The writer has observed these plants and agrees with the classification but wishes -1;0 add, that bluegra.ss (~ ap.) is probably more prominent than it was ~ 1918 in Consocies stipa. Very little bluegrass was observed ~n Consocies Bouteloua. This invasion of bluegrass may be due t~ pasturage which has be~n somewhat heavier during the winters of, the past few years. The field has been mown yoarly for many years, and the hay ha~ been removed. The fertility of the soil probably has not been de­ pleted greatly, because it has been fertilized with stable munure frequently to insure a continued good hay crop. The last appli­ cation of,stable manure was made in the spring of 1925 at a rate of about six tons per acre. Crops of the Surrounding Fields In 1925 oa.ts were grown in the fields south and. west of the station. These fields were in sweet corn and field corn in 1926. A permanent bluegrass pasture lies in the valley to the north. The field at the east was in timothy in 1925, but was put into field corn 1n 1926 except for a small corner at the northeast of the prair1e preserve. An old apple or~hard with -8- bluegrass lies along the east one-third of the south side. Methods of Colleoting Inseots The larger number of the inseots were oollected with the ordinary sweeping net. In 1925 very few inseots vlere tal::en from individual speoies of plants. In 1926 more time was spent in attempts to oollect from oertain characteristic species of plants. This was very difficult because of the scattered arrangement of all the plant species. Practically no pure stands of even several square feet in area are found in the field. The number of speoies of plants is comparatively large in relction to the size ot the traot. This tended to aid in collecting a large number of speoies of insects, but hindered the collection of large series of single species from one species of plant. In 1926 a number of speoies were secured from the surface of the soil. The oollecting started in 1925 on June 18, and stopped on August 21 when the field was mown. In 1926 the first col­ lection was made on l!urch 21, and the last on October 9. three days a~ter the field was mown. Collections were made about three times per week in each season, and usually in the forenoon from eight to eleven, or in the afternoon from t~o to five. Several night oolleotions, and early morning collections were ~ade in 1926. -9- Meteorological Data No meteorological data were secured in 1925.