THE COLORADO POTATO-BEETLE. 
147 
The perfect beetle (fig. 3) measures from two-fifths to half an 
inch in length, of an oblong-ovate form, and of a tawny or 
yellowish-cream colour, adorned with numerous black spots and 
stripes. Of the former, a very peculiar group, consisting gene- 
rally of eighteen, occupies the upper surface of the prothorax, 
or segment immediately behind the head. These consist of 
two elongated spots or short lines in the middle of the surface, 
a row of four small spots along the hinder margin, and usually 
six similar points on each side of the two middle ones. On the 
wing-cases (elytra) we see ten black stripes, five on each — 
namely, one close to the line of junction of the two wing-cases, 
and one close to the outer margin, both of which stop rather far 
from the apex of the wing-case, and three between these, 
reaching nearly to the tip. The edges of all these black stripes 
are irregularly punctured, the punctures being partly on the 
stripes and partly on the intervening pale surface, and the 
second and third stripes from the suture are in contact with 
each other at the base and apex (see fig. 5). The legs have the 
knees and the feet (tarsi) black. Beneath the elytra the insect 
is furnished with ample membranous wings, which it uses freely, 
and they are described by American entomologists as of a fine 
rose-colour, and as giving the beetles a very beautiful appear- 
ance when flying in the sun. 
The species appears to be pretty generally diffused in the 
Bocky Mountains, from the eastern slope of which it has in- 
vaded the cultivated regions by the course already described. 
Although found in the Colorado territory, it is by no means 
peculiar to that district, and the name of “ Colorado potato- 
bug ” commonly given to it does not indicate the locality from 
which it set out on its eastward journey. 
Although several American entomologists of repute (such as 
Messrs. Walsh, Riley, and Shimer) have devoted considerable 
attention to the habits of the Colorado potato-beetle, its history, 
at least in one important point, has not been very satisfactorily 
worked out. There appear to be three generations of the beetles 
in the year. In the spring, when the potato-plants are quite 
young, the perfect insects produced from the last generation of 
the previous year lay their eggs upon the under surface of 
the leaves in small patches of from twenty to thirty together 
(fig. 1, a). The number of eggs produced by each female is 
said by some writers to be from 700 to 1,200, but this is 
probably an exaggeration. The eggs are of a yellowish colour. 
They hatch in about six days. The larvse (fig. 1, 6, c, d ), 
which are at first of a reddish colour, grow rapidly, and be- 
come lighter in tint (of a more or less reddish cream-colour, 
or orange); they are full-grown in from seventeen to twenty 
days. In the mature state (fig. 1, d ) the larva is a thick fleshy 
