The Colorado Potato-Beetle. 
363 
tastes from the wild plants on which they naturally feed to 
cultivated products. 
The habits of the Chrysomelidce, at least in the active period . 
of their lives, are exposed to the light of day, and easily observed. 
The Colorado potato-beetle forms no exception to the rule, and 
this has rendered comparatively easy the application of remedies 
to its devastations. Like all other insects of the order to which 
it belongs, it undergoes transformations in its growth from the 
ezz to the adult or beetle-state : emerging from the egg as 
a grub or " larva," having six horny legs attached to the 
anterior part of the body, and a very convex and corpulent 
abdomen ; passing into the " pupa " or dormant state after about 
seventeen days of larval life ; and escaping from the ruptured 
skin of the pupa as a beetle at the end of ten days more. But 
the parent beetles, eggs, and larvae, are all confined to the leaves 
of the plant, the beetles and larvae feeding in broad daylight on 
the green leaves only, and completing their transformations 
during the summer months. The pairing of the male and 
female beetles, and the deposition of eggs, also take place on the 
j leaves. The only hidden features in the economy of the creature 
I are those attending the transformation of the pupa, and the 
I hybernation of the last brood of beetles at the end of summer. 
VVith regard to the former the process is as follows : — The larva, 
when fully grown, and after several successive changes of skin, 
enters the earth to change into the pupa state, forming a rounded 
cavity or chamber in the soil, the grains of which become some- 
what compacted, so as to form a sort of fragile earthen cocoon. 
It remains in this stage, as already observed, only about ten 
days, emerging from the ground at the end of that brief time as 
a perfect beetle, ready to commence a new generation. The 
hybernation of the beetles also takes place under ground. This 
is a point in the life-history of the insect of great importance in 
view of the chances of its importation into Europe, and, for- 
tunately, the testimony of American observers leaves us in no 
doubt as to the principal facts. Towards the end of the summer 
the last generation of the insect has been completed ; there 
remain no eggs or larvae on the plants, and the perfect beetles 
which survive do not pair (or, at least, lay no more eggs), but 
burrow their way beneath the soil, and there remain quiescent 
until the spring of the following year. The period when this 
takes place is before the chief crop of potatoes is taken out of the 
j ground, namely, in the month of October. This is in the State 
of Missouri, in a latitude and climate corresponding nearly to 
the extreme South of Europe. The beetles in hybernating do not 
descend generally more than 18 or 20 inches below the surface of 
' the soil, nor do they form a chamber of compacted earth, which 
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