- 195 - 
COLORADO 
.This is the fourth year in which collections were made in Colorado 
during the adult survey. In the 1938 survey 10,278 specimens were collected 
in 10 different environments. Disregarding Dissosteira longipenni s in the 
southeastern quarter of the State, there were 6 species of major importance. 
Ivlelanoplus mexicanus was first, at 16 percent of the total number collected; 
M. d ifferential is and M, femur- rubrum both at 11 percent; M. blvit talus at 
10 percent; M. lakinus at 8 percent; and Aeoloplus turnbullii turnbullii and 
A. turnbulli i brune r i together at 6 percent. On the range land M. mexicanus 
was the most numerous species other than D. longipenni s . It was also dominant 
in small grain, corn, sorghums, and restoration or idle land. There is no 
doubt that p-. mexicanus has increased in relative numbers in 1938 over some 
of the other species, although there is no marked change in the relative 
abundance of the important species. 
Hatching of D. longipenni s was first observed on April 29, and II. 
di f f e rent i al i s and M. bivi ttatus about May 15, continuing until the last 
week of June. Flights of D. longipenn i s began the last week of June and 
continued until about the first of October. The general movement was east- 
ward, and the 1938 surveys indicate that the infestations are again occupy- 
ing about the same areas as in 1937. The hopper infestations in crops are 
as heavy or heavier in the irrigated sections in the 1938 fall survey as 
they were, in the 1937 survey. Notwithstanding a. conservative estimate of 
a population reduction of 75 percent for D. longipenni s during the 1938 
season, the problem still remains about the same. The explanation for this 
lies in the. fecundity of the gras shoppers., which enables them to build up 
again within one season. About 4,500,000 acres is included in the general 
areas of the D. long! pennis infestations. 
