3 
- danger of confusing it with any related species or with beneficial 
ladybirds, a few words of description may be given. 
The beetle (fig. 1, a; fig. 2, 2) is of robust form, about three-eighths 
of an inch in length or a little more, and two-thirds as wide as long. 
It is ochreous yellow in color, and the wing-covers are ornamented 
with ten longitudinal black lines. The head is marked with a 
triangular black spot, and the thorax is dotted with ten or more 
irregular spots and other markings. The lower surface is also more 
or less marked with black, particularly the tarsi 
and knees. : 
The larve (fig. 1, 0; fig. 2, cc, d,d) are quite as 
weli known as the beetles and are very commonly 
called “slugs.” They are dark Venetian red 
when first hatched, and as they approach maturity 
become paler. They are slimy, disgusting looking 
creatures, soft m texture, and from their peculiar 
coloration and appearance would not be readily 
handled by anyone without gloves. 
The pupa is red like the larva and looks as 
Shown at ¢ figure ne 
The eggs (fig. 2, 6,0) are orange colored and are _ ta),an “old-fashioned 
deposited in masses. potatos Esa is 
thor’s illustration. ) 
As this beetle is sometimes confused with one or 
another of the “old-fashioned potato bugs” (blister beetles), a 
species of the latter is illustrated here for comparison (fig. 3). 
ORIGIN AND DISTRIBUTION. 
Tt has always been believed—and, the writer maintains, with rea- 
son, until the contrary can be proved beyond doubt—that the Colo- 
rado potato beetle, having become dispersed from Colorado as a start- 
ing point, originated as a species in that region. Dr. W. L. Tower, 
however, in a publication issued in 1906,¢ has assumed that this insect 
had the same origin as its principal wild food plant, Solanum rostra- 
tum, which he states is essentially tropical, and that the insect has 
followed the distribution of the plant from Mexico into Texas, New 
Mexico, and parts of Arizona. He also gives reasons for the belief 
that Leptinotarsa decemlineata has developed from L. “ intermedia 
Tower” after changing its habitat, the latter occurring in both 
Mexico and Texas, and the former not being found in Mexico at all, 
according to his experience. 
HISTORY OF THE INSECT’S SPREAD. 
The eastward dispersal of this potato beetle from what is generally 
considered its original home in the West is of peculiar interest. The 
«An Investigation of Evolution in Chrysomelid Beetles of the Genus Lepti- 
notarsa, Carnegie Institution, Washington, D. C., pp. 25 et seq. 
[Cir. 87] 
