THE ROCKY MOUNTAIN LOCUST. 
(GaJoptenus spretus Thomas.) 
Range of Species.— Iu the first report of the U. S. Entomological 
Commission this species has been fully treated, and the region over which 
it is found divided into the Permanent, Subpermanent, and Temporary 
*ifty iff ^: ^^ li 
(8 
cl 
Fig. 1. — Caloptenus spretus : Process of acquiring wings : a, pnpa with skin just split on the back; 
6, the iuiago extending; c, the imago neatly oat; d, the imago with wings expanded. ; e, the imago with 
all parts perfect, natural size (after Riley). 
regions. These may be briefly explained as follows : Permanent, that 
in which the locust breeds each year and is always to be found iu 
greater or less numbers; Subpermanent, that in which it is liable to 
breed for some years, when it multiplies in. excessive numbers iu its 
truly permanent breeding grounds, but from which it in time disap- 
pears ; Temporary, that over which the locusts migrate in years of ex- 
cessive abundance, but iu which they seldom breed and generally dis- 
appear within a year. The Permanent region embraces the greater part 
of Montana, a narrow strip of western Dakota, all but the northwestern 
quarter of Wyoming, the central and northwestern portion of Colorado, 
a small tract in north central Utah and southeastern Idaho, another 
similar tract in eastern Oregon and southern Idaho, and a very large 
area in the British possessions north of Montana which equals more 
than one-third of the whole region. The Subpermanent region lies im- 
mediately east of this, taking in a part of Manitoba, nearly all of Da- 
kota, the western half of Nebraska, and the northeastern quarter of 
Colorado. The Temporary region extends to within from 250 to 300 
miles of the Pacific coast, then taking iu northern Arizona and New 
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