PRESERVED INSECT FAUNA OF GLACIERS OF FREMONT COUNTY IN WYOMING - INSIGHTS INTO THE ECOLOGY OF THE EXTINCT ROCKY-MOUNTAIN LOCUST

From 1989 through 1992, preserved insect fauna of Knife Point, Bull La ke, and Upper Fremont glaciers (Wind River Range, Fremont County, Wyom ing) was examined. Knife Point Glacier contained the first intact, gla cially preserved grasshopper specimens found in the past 40 yr. These specimens were found below a crevassed region, and available evidence indicates that they may have been concentrated and preserved within a crevasse 140 +/- 50 yr ago. Morphological assessments of these bodies and cluster analyses of mandible and tibia measurements established th at all but one or two of the exposed deposits were comprised of the ex tinct Rocky Mountain locust, Melanoplus spretus Walsh. Examination of distinct summer-melt strata indicates that this species was deposited at random intervals over a period of 300 yr. The floating section of s trata also contained the first known glacial remains of swarms of the extant migratory grasshopper, Melanoplus sanguinipes (F.), and the fir st record of an insect other than grasshoppers (a parasitic wasp, Copi dosoma sp.) having been periodically deposited. A total of six insect orders was found on this glacier. Aerial and runoff samples indicated that the rate of accidental insect deposition on the glacier is very l ow, and the rate of loss of material from the surficial runoff may exc eed a million specimens per year. Bull Lake Glacier also contains at l east one very rich deposit of well-preserved M. spretus, but other gra sshopper remains appear to be widely scattered across the surface. Gra sshopper remains from ice cores of Upper Fremont Glacier were dated fr om as early as 840 +/- 85 yr before the present, making this the oldes t known glacially preserved insect deposit.