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Entomology Papers from Other Sources Entomology Collections, Miscellaneous

1991

Preserved Grasshopper Fauna Of Knife Point Glacier, Fremont County, , U.S.A.

Jeffrey A. Lockwood

Craig D. Thompson

Larry D. Debrey

Charles M. Love

Richard A Nunamaker

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Lockwood, Jeffrey A.; Thompson, Craig D.; Debrey, Larry D.; Love, Charles M.; Nunamaker, Richard A; and Pfadt, Robert E., "Preserved Grasshopper Fauna Of Knife Point Glacier, Fremont County, Wyoming, U.S.A." (1991). Entomology Papers from Other Sources. 48. https://digitalcommons.unl.edu/entomologyother/48

This Article is brought to you for free and open access by the Entomology Collections, Miscellaneous at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Entomology Papers from Other Sources by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Jeffrey A. Lockwood, Craig D. Thompson, Larry D. Debrey, Charles M. Love, Richard A Nunamaker, and Robert E. Pfadt

This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/ entomologyother/48 Arctic and Alpine Research, Vol. 23, No. 1, 1991, pp. 108-114

PRESERVEDGRASSHOPPER FAUNA OF KNIFE POINT GLACIER, FREMONT COUNTY,WYOMING, U.S.A.

JEFFREY A. LOCKWOOD,* CRAIG D. THOMPSON,t LARRY D. DEBREY,* CHARLES M. LOVE,t RICHARD A NUNAMAKER,t AND ROBERT E. PFADT*

ABSTRACT In 1987 and 1988, samples of preserved insects were extracted from the ice of Knife Point Glacier, Fremont County, Wyoming. The glacier lies at an altitude of 3500 m a.s.l. in the , , and is known to contain preserved insects. Although the glacier has undergone extensive recession in the last 50 yr, some insect deposits are still embedded at 20 to 25 cm below the surface and perhaps much deeper. The frozen deposits appear to consist entirely of grasshoppers. A few, virtually intact, specimens and body parts were in a state of preservation that allowed their identification as Spharagemon campestris McNeill and Melanoplus spretus (Walsh) or M. sanguinipes (F.). The majority of the deposits consisted of partial bodies and isolated parts, including, in order of frequency: mandibles, tibiae, tentoria, femora, wings (primarilytegmina), and cingulae/epiphalli. Deposits from various depths and locations on the glacier were radiocarbon dated at 205 + 65 to 450 + 80 yr BP. Although access to the glacier is quite difficult, the insects are better preserved than any glacial deposit documented in recent history. Thus, the state of preservation and age of the frozen deposits would suggest that additional, intensive sampling may be valuable in obtain- ing information on the ecology of grasshoppersprior to European settlementof North America.

INTRODUCTION

The Wind River Range glaciers in northwestern Wyo- Minor Glacier is 3 km south of Grasshopper Glacier. ming contain perhaps the richest deposits of glacially pre- Meier (1951) reported large amounts of grasshopper served grasshopper (Orthoptera: Acrididae) fauna in the remains on the surface of Minor Glacier; a collection of world. According to Meier (1951) and Henderson (1933, grasshoppers and other insects was unfortunately lost on 1939), these glaciers, extending along the Continental the way back from the glacier so the species composition Divide, include at least five glaciers with frozen grass- is not known. The deposits were apparently relatively hoppers. Grasshopper Glacier is the northernmost of the recent in origin or were exposed during glacial recession, deposits. It is the largest glacier bearing this name (there since the remains were not completely embedded in the are four other glaciers named Grasshopper or Hopper ice. glacier) and, as recently as the last 10 yr, contained large Mammoth Glacier lies about 0.5 km south of Minor numbers of specimens (Watson, pers. comm., 1989). Glacier. Henderson (1933) reported large numbers of rotting grasshoppers on the surface of this glacier. Later observations omit reference to of Soil and Insect any grasshoppers (Meier, *Department Plant, Sciences,University and it be that near the of Wyoming,Laramie, Wyoming 82071, U.S.A. 1951), may presumed deposits have been lost. tWaterQuality Laboratory, Western Wyoming Community surface College, Rock Springs, Wyoming 82902, U.S.A. Henderson (1939) discovered "billions of grasshopper tArthropod-borneAnimal Diseases Laboratory, Agricultural carcasseswhich stank horribly"on the surface of Fremont Research Service, U.S. Department of Agriculture, Laramie, Glacier, about 8 km southwest of Grasshopper Glacier, Wyoming 82071, U.S.A. but later reports (Meier, 1951) made no referenceto grass-

108 / ARCTIC AND ALPINE RESEARCH ?1991 Regents of the University of Colorado hoppers at this site. On the basis of Henderson's (1939) biologist has collected material from any of the Wind description, it appears that at least a significant portion River glaciers. However, the lack of collection is un- of the deposits have been lost. doubtedly due to both the limited information available Knife Point Glacier lies 10 km southwest of Grass- on these sites and the relative inaccessibility of the gla- hopper Glacier. Since Henderson (1939) noted the ciers (e.g., Knife Point Glacier is 35 km from the nearest presence of grasshoppers and Meier (1951) did not, we trailhead). Thus, in 1988 and 1989 we undertook a study can assume that a portion of the deposits have probably to determine the following characteristics of the most been washed from the glacier during recession in the last accessible of the Wind River glaciers, Knife Point Gla- 50 yr (Love and Thompson, 1987). cier: the distribution of grasshopper specimens in the gla- Given the potential value of glacially preserved insect cier, the degree of preservation of the deposits, the date fauna (e.g., the opportunity to deduce the mechanism of of deposition of the specimens, and the grasshopper extinction of the Rocky Mountain locust, Melanoplus species present in the ice. Since there are no preserved spretus (Walsh) in the late 1800s [Lockwood and DeBrey, samples from the Wind River glaciers, we were also inter- 1990; Lockwood et al., 1990a]), it is surprising that no ested in collecting material as a resource for future work.

FIGURE1. Location of Knife Point Glacier within the Wind River Range of western Wyoming, U.S.A.

J. A. LOCKWOOD ET AL. / 109 RESEARCH SITE AND METHODS

Knife Point Glacier is located at 3500 m a.s.l. in were counted from a 10 g subsample of the material. Fremont County, Wyoming, in the Shoshone National Four samples (0.2 to 1.0 g) of the material from Knife Forest, Wind River Range (U.S. Geological Survey, Point Glacier were submitted to Beta Analytic (Coral Fremont Peak South Quadrangle, N4300-W10930/7.5, Gables, Florida) for radiocarbon dating. The samples Figures 1 and 2). The glacier lies 35 km northeast of Pine- were combusted in an enclosed system. The carbon dale, Wyoming. Observations of insects on the glacier's dioxide was collected and purified and then reacted with surface were made in 1985 and 1986. Samples of pre- hydrogen on cobalt catalysts to produce graphite. The served insects and insect parts within the ice were collected accelerator-AMS measurements were made in triplicate in duplicate from two sites (sites A and B) within a single at the Eidgenossische Technische Hochschule, Zurich, layer of the ablation zone in August 1987 by C. D. Switzerland. The dates were adjusted based on the Thompson (Figure 2). These samples were collected 150 m standard correction for '3C/'2C. To allow determination upslope from the terminus, 20 to 25 cm below the surface, of the dating precision and to attain the greatest areal by chipping with an ice axe or sampling from exposed spread we chose a pair of samples from the same insect- summer surfaces. Insect samples were collected from five bearing layer (sites A and B), one sample from the deepest sites in August 1988 by C. M. Love. Two sites (C and D) layer (site D), and one sample from the richest layer (site represented the lowest insect-bearing layers, ca. 100 m F). upslope in the ablation zone. Site E represented a com- The identity of the grasshopper species collected from posite of material washed from several layers during gla- the glacier was determinedusing available taxonomic keys cial recession. The richest, insect-bearing layer was and diagnostic structures (e.g., male genitalia). Once a collected from two sites (F and G), some 100 m above definitive identification to genus was accomplished, the terminus in the ablation zone. The principal purpose of the glacial work was the collection of geological and hydrological data, so the insect samples were oppor- tunistically collected in areas of likely deposition and exposure.Given logistical constraints, it was not possible to gatherrepresentative samples from a wide varietyof locationsor to systematicallysurvey the glacierto deter- mine the distributionof preservedinsects. However, extensivefield notes and observationsduring the course of geological surveys provided some indication of the likely locations and distributionof the frozen insects. The condition and state of preservationof the grass- hopperdeposits were described.Samples were collected usingice axes, chippingtools, and stainlesssteel forceps; the material was wrappedin aluminumfoil and kept frozenby dry ice in a cooler for returnto the laboratory, ;1. ? where the deposits were stored at -5?C. Because the ; II did not include amountsof soft tissues -t. deposits significant ,, suitablefor or related the mate- i:Cy ?.:f?.lIL.j*?L;;j;_:E1. r,t=r ? electrophoretic analyses, -??-?rre .t i'?icriri" rial was subsequentlythawed, dried in glass under a ''t'???.?l 2LEcyk '' in **U -'LICL laboratoryhood, and stored glass at 22?C. After dry- 5. . ~c?? r ;?_s*C;;F;lg*;;- the materialwas teased in an effort l?kkj, ing, carefully apart -. C* to of whole bodies tcC. 3tr preservefragile portions grasshopper `4zTa1, "d -?---?,: ? ;* intact. The and abundanceof u= ;1 types specificgrasshopper --" in the materialcollected from each site 'rLJi;t? L-? I parts sampling r L?C:Cit,Llr: :s? were A of less than r; t catalogued. complete analysis samples ?3 ', ""iL r 10 g was performed. For samples over 50 of q fXr: including g ;cCi;tJR..?'' u;* material, the entire sample was censused for whole and 1;Y,'** ? 7f_YIh_-? I"" '* -4 partial bodies and large and rare '.?1FC body parts (i.e., tegmina 5i;a- [the leathery forewings], epiphalli [a sclerotized or hardened area in the floor of the male genital chamber], cingulae [a sclerotized or hardened area of the male geni- talia], and femora [the third and largest segment of the leg]); smaller, abundant body parts (i.e., tentoria [the endoskeletal support structure of the head], tibiae [the FIGURE2. Ablation zone of Knife Point Glacier, Wyoming. fourth segment of the leg, distal to the femur], and Collectionsites A and B werewithin the depictedinsect-bearing mandibles [the biting, jawlike appendages in the mouth]) layers.

110 / ARCTIC AND ALPINE RESEARCH morphometric analyses were attempted for purposes of tion of males and females in the deposits. In many cases, identifying the remains to species (Lockwood, 1989). it was necessary to reasonably extrapolate the size of a Because the sex of the individual body parts could not body part because a portion of the part was missing (e.g., be determined, it was necessary (but perhaps not entirely the end of a tegmen). accurate [e.g., Popov, 1954]) to assume an equal propor-

RESULTS AND DISCUSSION

The glacially preserved insects of Knife Point Glacier resulted from the fallout of one or more large swarms have undergone a considerable degree of dismemberment. of migratory grasshoppers, rather than a chronic input We were able to recover 26 partial bodies (representing of insects from surrounding alpine habitat, as seen on at least 21 individuals), variously consisting of partial Grasshopper Glacier, Crazy Mountains, Park County, thoraces, tegmina, and abdomens. It would appear that Montana (Lockwood et al., 1990b). Thus, the deposits there have been some glacial terminus changes in the last on Knife Point Glacier resemble those on Grasshopper 500 yr, including advances during the Little Ice Age (1300 Glacier, Beartooth Mountains, Park County, Montana to 1800 A.D. [Grove, 19881)and dramatic recessions dur- (Lockwood et al., 1990a). In order of abundance, the ing the last century (Marston et al., 1990). Indeed, the deposits consisted of mandibles, tibia, tentoria, femora, terminus of Knife Point Glacier has receded 228 m since wings, cingulae, epiphalli, and partial bodies (Table 1, 1963 (Love and Thompson, 1987). Glacial flow has Figure 3). Clearly not all sites had the same distribution caused considerable shearing of fragile materials within of these body parts (e.g., no mandibles were found at the ice. Some deposits (sites E-G) are now exposed at the site Al, and 31 mandibles were found at site B2). How- surface of the glacier and appear to be undergoing decom- ever, the general distribution of body parts is very similar position. Despite the forces of shearing and decomposi- to that found on Grasshopper Glacier in the Beartooth tion, the deposits are generally in better shape than any Mountains (Lockwood et al., 1990a), although there were other glacially preserved insects studied in recent years relatively more mandibles and fewer femora in Knife (Lockwood et al., 1990a, 1990b). The existence of deeply Point Glacier. The most heavily sclerotized body parts embedded layers (sites A and B) is particularly encourag- (mandibles and tibiae) have survived the shearing and ing with regard to the potential for further work follow- decomposition processes. Moreover, it appears that the ing more thorough collection. vast majority of the grasshoppers in the primary, insect- A number of insect taxa were found on the surface of bearing layers belong to a single species; the size and color the glacier, including Lepidoptera (butterflies [family (e.g., red to pink tibiae) of the body parts is uniform, undetermined] and moths [probably Noctuidae]), virtually without exception. It had previously been Hymenoptera (bees [Apoidea] and ants [Formicidae]), assumed that the assortment of body parts found on the Orthoptera (grasshoppers [Acrididae] and crickets [Gryl- surface of Grasshopper Glacier in the Beartooth Moun- lidae]), and Odonata (dragonflies [family undetermined]). tains was a result of decomposition (Lockwood et al., However, the subsurface deposits appear to be restricted 1990a). Based on the composition of deeply buried insect- to distinct layers and consist solely of grasshoppers.These bearing layers on Knife Point Glacier, it appears that the characteristics are consistent with the deposits having disproportionate number of hardened body parts may

TABLE 1 Distribution of preserved grasshopper body parts collected from Knife Point Glacier, Wyoming Numberof Weight Sitea (g, dry) Mandibles Tibiae Tentoria Femora Wings Genitaliab Al 30 31 2 8 1 5 3 A2 7 0 5 1 0 4 0 B1 18 19 1 0 0 6 1 B2 24 0 19 0 11 0 0 C 3 0 25 0 13 0 1 D 10 37 15 39 9 14 3 E 72C 1010 120 320 80 20 0 F 60c 512 112 136 15 9 2 G 4 0 24 0 11 1 0

aSee Methods section for site descriptions. bGenitalia include cingulae and epiphalli. CNumbersof mandibles, tibiae, and tentoriae are extrapolated from a 10-g subsample.

J. A. LOCKWOODET AL. / Ill resultfrom degradationprocesses that occureven before mesothorax(Figure 3). None of the grasshopperbodies a depositbecomes exposed to the surface.This may result had retainedtheir markings or color. All four of the iden- from anaerobicdecomposition of the insect-bearinglayer tifiablebodies were female; two appearedto be Spharage- withinthe ice or from aerobicdecomposition as oxygen- mon campestris and two were Melanoplus sp. rich meltwaterpercolates through the layer. The S. campestrisfemales were recognizable from the Radiocarbondating of samples from sites A and B, shape of the intermetasternalspace, incisions on the within a common layer, revealed ages of 205 65 median carina, metazona:prozonaratio, and general (Beta-32624,ETH-5688) and 330 65 yr (Beta-32623, body structure(Capinera and Sechrist,1982; Otte, 1984). ETH-5687),respectively. The overlappingvariances on Weare confidentof the genusidentification, but because these values suggest an acceptabledegree of precision. the wing colorationand other diagnosticbody markings However, the differencein these dates may imply that wereobscured, the speciesdesignation is less certain.This this insect-bearinglayer is composedof the accumulation speciesmay be foundat highaltitudes (Gilette, 1904), and of morethan a singledepositional event. Indeed,two or the source of the specimensfrom the glaciermay have more layersmay be combinedduring a warm summer, been a local, alpine habitat. a yearof low snowfall,or a combinationof meteorologi- The Melanoplussp. females'genus was easily deter- cal conditions.As expected,the insect layer outcropon minedby the distinctconical spine insertedbetween the the summersurface, closest to the glacierterminus, con- front legs (Capineraand Sechrist, 1985). However, the tained the oldest insects; sites D and F had ages of identification of Melanoplus species depends almost 410?65 (Beta-32625, ETH-5689) and 450?80 yr entirelyon characteristicsof the male genitalia, so the (Beta-32626, ETH-5690), respectively. These dates wholebodies could not be identifiedto species.However, suggestthat depositionalevents may havebeen relatively the preservedepiphalli and cingulaewere clearlythose frequentand that they occurredprior to Europeansettle- of M. sanguinipes or M. spretus (Walsh); they were vir- ment of the westernUnited States. These dates do not tuallyidentical to those recoveredfrom Grasshopper Gla- agreewith a count of approximately500 supposedsum- cierin the BeartoothMountains, where the depositshave mer surface exposuresabove sites A and B (Figure2). been tentativelyidentified as M. spretus.Morphometric This large discrepancyis not easily explained,but one analysesof diagnosticbody partswas equivocal(Table 2). possibleexplanation is that two distinctinsect/particulate Unfortunately,there were few morphometricallydiag- depositionalevents (i.e., seasonalwind-blown material) nostic body partspreserved, and those of greatestvalue occur each year. We are pursuing several avenues of (i.e., diagnostic for both sexes) did not consistently researchthat mayeventually solve this discrepancy.How- supporteither species. Perhapsit should be noted that ever,until such time it wouldseem most judicious to con- one entiretegmen measured 23.84 mm, which is within siderthe radiocarbonages as havingthe greatestaccuracy. the rangeof M. spretusand well outsidethe rangeof M. Of the 26 partialbodies extracted from the glacialmate- sanguinipes (Lockwood, 1989). Given the age of the rial, only four were in a state of preservationthat per- deposits,the densityof grasshopperswithin the deposits, mitted taxonomic identification.The remainingbodies andthe biologyof rangelandgrasshoppers, it appearsthat were crushedand fragmented,often comprisedof only KnifePoint Glaciermay contain a remarkablyrich supply a few abdominalsegments and portionsof the meta-and of the extinct Rocky Mountainlocust (Lockwood and

FIGURE 3. Partial and intact bodies of grasshoppers extractedfrom the ice of Knife Point Glacier,Wyoming.

112 / ARCTIC AND ALPINE RESEARCH TABLE2 Morphometric comparisons of diagnostica characters in Melanoplus sanguinipes, M. spretus, and specimens from Knife Point Glacier, Wyoming Source Measurementb M. sanguinipes M. spretus Glacier Lengthof sternum 5.77 + 0.71 6.42 ?0.53 5.04 0.00 ( 1) Diameterof eye 1.50?0.14 1.56?0.11 1.82 0.79 ( 2) Height of pronotum 4.16?0.29 4.41 ?0.32 4.07 ?0.66 ( 4) Length of pronotum 5.88 ?0.38 5.06 ?0.28 4.390.11 ( 3) Min. width of pronotum 3.39 ? 0.28 3.84 ?0.27 3.56? 1.75 ( 3) Max. width of pronotum 4.40 ?0.43 4.82 0.34 4.62?1.15 ( 3) Lengthof metazona 2.50 0.24 3.04 ? 0.22 3.57 0.21 ( 3) Lengthof tegmen 19.57 ? 2.02 25.36 ? 2.60 22.93 + 3.67 (28) aOnlythe maximumwidth of the pronotum,length of the metazona,and length of the tegmen are diagnosticfor both sexes; the other measurementsare diagnostic for one of the sexes. bMeasurementsare in mm and expressedas the mean + standarddeviation; N for M. sanguinipesis 125;N for M. spretusis 124;and N for the glacialspecimens is given parenthetically.Measurements of M. sanguinipesand M. spretus are taken from Lockwoodand DeBrey(1989).

DeBrey, 1990). Further collections and investigations will hopper species are a natural phenomenon; data from gla- be necessary to clearly establish if this is the case. cial deposits may allow us to test this assumption. Our Finding fully embedded, relativelywell preservedspeci- approach to management of rangeland grasshoppers mens of grasshoppers in the ice of Knife Point Glacier should be heavily dependent on whether population suggests several future directions for research. First, the explosions of these animals are a recent aberration or an possibility that intact specimens exist in the other Wind evolutionarily stable process. Finally, the data derived River glaciers now seems highly reasonable. The collec- from preserved specimens may provide an answer to the tion of material from these other sites may provide valu- sudden and unexplained extinction of M. spretus in the able information on the ecology and biology of grass- late 1800s. Without accurate knowledge of its biology hoppers on undisturbed ecosystems that no longer exist (e.g., host plant associations, pathogen loads, genetic in North America. Second, the need for more thorough condition) prior to the 1800s, the only extinction of an collection of specimens from Knife Point Glacier is immi- insect pest species remains largely a matter of deductive nent. The glaciers in North America are rapidly receding speculation (Lockwood and DeBrey, 1990). (as much as 90% in the last 85 yr) and valuable material has already been lost from at least one important site (Lockwood et al., 1990a). If entirely intact specimens can ACKNOWLEDGMENTS be collected, we will be able to determine host plant utili- zation, pathogen loads, and other biological properties We thank M. Sanchez for her invaluableassistance and in the of grasshopper species under prehistoric conditions. It patience separationand sorting of insect parts. has been assumed that outbreaks of rangeland grass-

REFERENCES CITED

Capinera, J. L. and Sechrist, T. S.,1982: Grasshoppers of Melanoplusspretus (Walsh) with solitaryand migratory (Acrididae)of Colorado.Colorado State UniversityExperi- Melanoplussanguinipes (F.). CanadianEntomologist, 121: ment Station Bulletin 584S. 1103-1109. Gillette,C. P., 1904:Annotated list of ColoradoOrthoptera. ,1939: The WindRiver Range of Wyoming,supplement. Colorado AgriculturalExperiment Station Bulletin, 94: Appalachia,22: 47-56. 17-67. , 1990: A solution for the sudden and unexplained Grove, J. M., 1988: TheLittle Ice Age. New York:Methuen. extinctionof the RockyMountain Grasshopper, Melanoplus 498 pp. spretus(Walsh). Environmental Entomology, 19: 1194-1205. Henderson,K. A., 1933:The Wind RiverRange of Wyoming Lockwood, J. A., Nunamaker,R. A., Pfadt, R. E., and II. Appalachia, 19: 354-375. DeBrey,L. D., 1990a:Grasshopper Glacier: Characterization Lockwood,J. A. and DeBrey,L. D., 1989:Taxonomic status of a vanishingbiological resource. American Entomologist, of the RockyMountain Locust: Morphometric comparisons 36: 18-27.

J. A. LOCKWOODET AL. / 113 Lockwood, J. A., Burne, J. C., DeBrey, L. D., Nunamaker, American Water Resources Association. R. A., and Pfadt, R. E., 1990b: The preserved fauna of Meier, M. F., 1951: Glaciers of the -Fremontarea, Grasshopper Glacier (Crazy Mountains, Montana): Unique Wyoming. M.S. thesis, State University of Iowa. 159 pp. insights to acridid biology. Proceedings of the 5th Interna- Otte, D., 1984: The North American Grasshoppers. Volume II, tional Conference of the Orthopterists' Society, Valsain, Acrididae: Oedipodinae. Cambridge: Harvard University Spain. Press. Love, C. M. and Thompson, C. D., 1987: Stratigraphy and Popov, G. B., 1954: Notes on the behaviour of swarms of the recent melting of the Wind River Glaciers, Wyoming. Desert Locust (Schistocerca gregaria Forskal) in Iran. Anti- Proceedings of the XII International Union for Quaternary Locust Bulletin, 14: 1-32. Research Congress, Ottawa, Canada. Watson, W., 1989: Personal communication. Marston, R. A., Pochop, L. O., Kerr, G. L., and Varuska, J. L., 1990: Recent trends in glaciers and glacier runoff. Wind River Range, Wyoming. Proceedings of a Symposium of the Ms submitted June 1990

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