318 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



Kange a grasshopper new to science would one day be collected far 

 from its native surroundings and be given his name ! 



But vastly more significant, from the standpoint of a field biolo- 

 gist, were my collections in Big Smoky Valley, and other localities 

 where migrations had occurred a few years earlier, for they showed 

 that rugglesi still existed there, though in scattered numbers, and 

 the wings were shorter than in migrating swarms ! A few specimens 

 that obviously were completely solitary in phase characteristics were 

 found in collections of grasshoppers taken at several localities in 

 years before the important infestations began. Accordingly, phase 

 transformation evidently occurs in rugglesi, though additional ob- 

 servations are required to supply the complete details of the changes 

 that take place and the ecological conditions producing them. 



The specimens of rugglesi found alive on Grasshopper Glacier 

 were clearly distinct from the related M. occidentalis which inhabits 

 the surrounding area of Montana and Wyoming and practically 

 all the Rocky Mountain and northern Great Plains regions. The 

 long wings, well-indicated by the E/F ratio, were typical of the 

 optimum gregarious phase such as represented in migratory flights. 



DISTRIBUTION OF MELANOPLUS RUGGLESI AND PROBABLE SOURCE OF 



GLACIER SPECIMENS 



In 1949 the gregarious phase of rugglesi was known only in north- 

 western Nevada, northeastern California, and southeastern Oregon 

 (mainly in the vicinity of Denio), in any case a distance of at least 

 500 miles from Grasshopper Glacier. A single specimen in the soli- 

 tary phase was collected near Arco, Idaho, by Rehn and Hebard in 

 1928, and another of the same phase was taken at Rock Springs, Wyo., 

 by Rehn in 1922. Field work may eventually disclose colonies of 

 the gregarious type in southern Idaho and thereby suggest the pos- 

 sibility of their unreported presence there or at other localities in 

 1949. Owing to the widespread movements of rugglesi when migrat- 

 ing, however, and the phase changes that occur, collections made after 

 1949 will be unreliable indicators of what occurred in 1949. Mean- 

 while, it is helpful to examine circumstantial evidence suggesting 

 that a 1949 movement to the glacier from Oregon or Nevada may 

 have taken place. 



Immediately after August 1, 1949, field men assigned to grasshopper 

 survey work by the United States Bureau of Entomology and Plant 

 Quarantine who were located in range areas both west and east of 

 Grasshopper Glacier were alerted to watch for rugglesi in conjunc- 

 tion with their regular duties. No trace of rugglesi was found, though 

 occidentalis was collected and submitted for checking. 



In July 1949 extensive flights of rugglesi occurred in the infested 

 area of Oregon and Nevada, and they remained in progress up to 



