1874. ] 
THE COLORADO POTATO BEETLE. 
77 
their work of destruction, which they continue for about three weeks, when they 
retire beneath the ground and pass through the pupa stage, to appear again in a 
fortnight as perfect insects, and soon multiply their species a thousandfold. How 
long the parent beetles exist we have no authentic information, but we think it 
may be assumed that having accomplished the act of reproduction, they speedily 
die ; but at any rate there is little doubt that the members of the last brood of 
the season having reached the perfect state, hibernate in the soil, and possess the 
ability to penetrate to such depths that frost and ploughing have little or no 
effect upon them, specimens having been found eight and ten feet below the 
surface, though the more general distance is from 18 in. to 2 ft., while some do 
not enter the ground at all, but secrete themselves beneath suitable substances 
in favourable localities. The worst of the matter is, that when once the beetle 
obtains a footing in any locality, there it will probably remain for all 
time; for it travels by spreading, not by migrating from one district to 
another; and although in some seasons it may be less disastrous in its 
operations than in others, it will always be ready to take advantage of favourable 
opportunities. 
It may be asked in what state the beetle may be expected to arrive, and by 
what means it may be distinguished. The answer to the first part of the ques¬ 
tion may be surmised from the brief life-history above given, for it does not 
appear possible that the insect can reach this country save in the perfect state. 
The advice has been tendered that those seedsmen who import American tubers 
should be careful to see that they do not also import the Doryphora; but it is 
difficult to see how it should be packed with the seed unless placed there inten¬ 
tionally, and even then it would probably perish, and would invariably be dis¬ 
covered in the warehouses here. It is tolerably certain that it cannot reach this 
country in the egg state, and as there is ample reason to believe that it never 
hibernates in the pupa stage, which is, too, of short duration, the only way it can 
possibly reach this country is by alighting on vessels lying in the ports on the 
Atlantic coast of America. Stowed away in the hundred and one nooks of the 
numerous traders between the States and Europe, the beetle would experience 
little difficulty in surviving the voyage, and as we have shown, one female safely 
landed would speedily found a colony. 
The perfect insect is about half an inch in length, and 5-16ths in breadth, 
the ground-colour of the elytra being of a creamy-yellow, marked, as the specific 
name implies, with ten longitudinal black stripes, five on each wing-case, the third 
and fourth of which unite at the base. It might be doubted whether the 
Doryphora would find our climate suited to its constitution, but the experience 
of the Americans negatives all hope of that kind, for as a matter of fact, the 
beetle has spread more rapidly northwards than southwards. In April and the 
sunnier weeks of spring, it delights in warm and comparative dryness, and if 
tempted too early from its winter quarters, speedily returns to them, if the 
weather becomes cold and wet. A hot dry summer, however, is fatal to large 
numbers of the larvae and even the perfect beetles, which cannot enter the hard- 
baked earth, and consequently die. Such summers as those, however, are not 
the rule here; so that, as far as we can judge with our present knowledge of 
Doryphora^ it would probably flourish amazingly in this country. The remedies 
found most effectual in America are dusting the plants with a mixture of Paris 
green and flour or plaster, a very small quantity of which will kill any larva or 
perfect insect with which it comes in contact; but this powder is highly 
poisonous, and requires to be used with care. The best time for performing the 
operation is in the cool of the morning, when the dew is still on the leaves and 
