3G(> 
Tlie Colorado Potato-Beetle. 
must attend all efforts to resist it. He reports that in 1871 the- 
Detroit River, separating the State of Michigan from Canada, 
was literally swarming with the beetles, and that they were cross- 
ing Lake Erie on ships, chips of wood, staves, boards, or any 
other floating object which presented itself. " They soon in- 
fested all the islands to the west of the lake, and by June they 
were common around London (Canada), finally occupying the 
whole country between the St. Chair and Niagara rivers " (lat. 
43° N., corresponding to the south of France). In the spring of 
1871 the beetles swarmed in the streets of St. Louis, Missouri. 
They were said about the same time to have appeared in im- 
mense numbers on a potato patch belonging to Indians on the 
northern shore of Lake Superior (in lat. 48°, corresponding to- 
the north of France), although no potatoes were cultivated 
within 150 miles of the place ; thus making a leap which it was^ 
very difficult to account for. In the summer of 1873 the waters 
along the southern shore of Lake Erie, at the place where it is 
broadest, were again observed to be swarming with the living 
beetles, and at Painesville, in Ohio, clouds of them were seen, 
flying westward, composed, according to a newspaper report, of 
tens of thousands of individuals. Their occurrence in abun- 
dance on the shores of lakes and on floating substances is, no- 
doubt, to be accounted for by their having been precipitated 
into the water owing to the collapse of their powers whilst blindly 
attempting to fly across a broad expanse of water. I have often 
had occasion to notice a similar phenomenon on the borders 
of the riverine lakes of South America, where in the morning, 
after a squally night succeeding a sultry evening, continuous- 
ridges, composed of half-drowned winged insects of all orders, 
and including even small birds, have been found cast up by the 
waves. Swarms of migrating " lady-bird " beetles are sometimes 
seen congregated on the southern and eastern coasts of England ; 
and occasionally numbers of them have been found in a drowned 
state cast up on the beach, the result of their vain attempts to 
fly across the channel ; but more frequently their instinct serves 
them better, and they try to go no further, for to this cause 
appear to be due the vast assemblages of these insects noticed in 
some seasons in our southern maritime districts. 
Last summer the beetle reached the maritime districts of the 
middle Atlantic States. Accounts were published in England 
of its having devastated potato-fields in Pennsylvania in the 
month of August, and injured the growth of the tubers to that 
extent that it did not repay the trouble to take them out of the 
ground. In fields that were not attacked till September the 
plants above ground were quickly destroved, but in such cases 
the tubers, having attained their growth iicfore the leaves were 
