IM 



l)}vcrtchnites — Our Living Hi'soiirces 



points in time. The only such case involving 

 grasshoppers that I am aware of involves the 

 ranges of two grasshopper species along the 

 Great Lakes shores. Trimerotropis hurouiaiui 

 and T. maritinui displace one another on the 

 dunes suiTounding the Great Lakes, witii T. 

 Iiitroniaihi occupying the northern shores and J] 

 mahtima the southern shores (Otte 1970). The 

 boundary between these two species has shifted 

 in the last seven decades. The two species may 

 well be competitive on four different lakefronts, 

 on the north-south shores of Lakes Michigan 

 and Huron. 



Prairie Peninsula 



In southern Michigan the bandwing 

 grasshopper {Panlalophora hahleinaui) was 

 abundant in 1943 and the related species. P. 

 apiciilata. was rare (Cantrall 1943). By 1968 P. 

 hahicmani had been completely replaced by P. 

 apiciiliitci. probably because subtle habitat 

 changes gave P. apicukiui an advantage over the 

 strictly prairie species P. haldemaui. 



Unnatural Range Increases 



Precise documentation of range changes in 

 grasshoppers could be achieved if historical col- 

 lecting sites could be resurveyed today. We arc 

 reasonably certain, though, that the cutting of 

 eastern forests (mainly during the last century) 

 opened up habitats for numerous species adapt- 

 ed to grasslands and forest edges. Numerous 

 prairie margin species now occur widely in the 

 eastern LInited States in areas that were almost 

 completely covered by forests. By colonizing 

 roadsides, other species have become extremely 

 widely distributed. The Carolina locust 

 {Dissosteini Carolina), for example, is a ubiqui- 

 tous roadside species that is now found in pre- 

 viously heavily forested regions. Whether the 

 overall range (outer limits of the range) has 

 changed is debatable because the species inhab- 

 its river margins and small natural eroded areas 

 within the eastern forest region. 



In the western L'nited States, certain species 

 do well in eroded habitats that often result from 

 overgrazing. Thus, the ranges of species spe- 

 cializing on eroded ground probably increased 

 along with increases in grazing. The clear- 

 winged grasshopper (Cawnula pellucida), a 

 pest species from the northern Great Plains that 

 greatly damages crops in the northern LInited 

 States and western Canada, is now extremely 

 abundant in overgrazed mountain meadows in 

 the western states and is a good indicator of 

 meadow degradation there. 



Many pest species specialize on agricultural 

 fields; their ranges have increased because of 

 irrigation and the planting of crops in normally 

 desert habitats (e.g.. migratory grasshopper 



[Melanopliis sangiiinipes], two-striped 

 grasshopper [M. hivittatus], and differential 

 grasshopper [A/, dijferentialis]). Ball et al. 

 (1942) documented numerous cases of 

 grasshoppers moving into areas altered by agri- 

 cultural practices. 



Range Reductions and 

 Extinctions: Case Studies 



The Rocky Mountain Locust 



Although it was the most abundant species 

 during much of the last century in western 

 North America, the Rocky Mountain locust (M. 

 sprctus) is now extinct; no specimens have been 

 collected in this century. This species spread its 

 destruction over many western states and was 

 the source of great difficulty for early farmers 

 east of the Rocky Mountains. The complete dis- 

 appearance of the species has puzzled biologists 

 for decades. The most reasonable hypothesis is 

 that this species reproduced mainly along river 

 valleys in Montana and Idaho and that with the 

 heavy grazing of these habitats, beginning in the 

 last part of the 1800's. these breeding areas 

 were so heavily disturbed that breeding was dis- 

 rupted (Lockwood and DeBrey 1990). Today, 

 frozen remains of this species can still be found 

 in glaciers in Montana. 



California Coastal Ranges 



The ANSP collections revealed that two 

 undescribed species o'i Melanopliis were collect- 

 ed only in what is now downtown San 

 Francisco. Recent revisions of the Marginatus 

 group of the genus Melanopliis (Otte I98I. 

 1994. unpublished data base) reveal that the 

 coastal ranges of California contain numerous 

 members of this group, but that the ranges of 

 many of the species are extremely limited. A 

 subgroup of the Marginatus group speciated 

 around the San Francisco Bay area, two species 

 are known from the Berkeley area, two from San 

 Francisco proper, and several from the north 

 side of San Francisco Bay. The San Francesco 

 species were collected in the first decade of this 

 century when some natural vegetation still exist- 

 ed in San Francisco. South of San Francisco 

 these species are replaced by related species. 

 Several other species in the group are known 

 only from the Monterey Bay region, and one 

 species only from a single locality. 



Two Rare Species 



Two individuals of an extremely rare 

 grasshopper species (E.xiniacris siiperbiim 

 Hebard) were collected in south Texas. 

 Repeated efforts to collect the species have not 

 met with success, although the species possibly 



