Tke Colorado Potato-Beetle. 
365 
met with in the same region. Here for years after its discovery 
it lived, as before, a harmless life, like the rest of its congeners, 
and was by no means a common insect. According to Mr. Ben- 
jamin Walsh, State Entomologist for Illinois, it was only when 
the cultivation of the potato reached the base of the Rocky 
Mountains, with the advance of colonisation westward, that the 
creature displayed a taste for the introduced plant, so nearly 
allied to the economically worthless one which constituted its 
native food. It was first noticed in potato-fields in 1859, about 
100 miles west of Omaha, in Nebraska, and was at that time 
spreading rapidly eastward. In 18G1 it invaded Iowa, the next 
State on the east, and in 1864 and 18G5 it crossed the Mis- 
sissippi into Illinois. The sudden appearance of a new foe to 
the popular esculent, and the destruction it caused to a crop of 
such great domestic and commercial value, filled the Western 
farmers with dismay, and the local newspapers teemed with 
accounts of the havoc it was causing. In the warm weather, 
towards the end of spring, the beetles and their voracious larvae 
swarmed over the fields, and in a few hours denuded the grow- 
ing plants of their tender leaves ; effectually arresting the growth 
of the tubers. Their work completed in one district, the beetles 
took to the wing and migrated to others. Barns, houses, sitting- 
rooms, and bedchambers were invaded by the encroaching pests. 
In 1866 they overran the Southern parts of Wisconsin ; in 1867 
they passed into Indiana (east of Illinois), and spread over its 
borders into Ohio ; in 1870 they crossed the broad St. Clair 
River and entered Canada. By 1873 the onward-spreading pest 
had reached Quebec, and, further south, had entered the States 
of Vermont, New York, New Jersey, Pennsylvania, and Mary- 
land. The prophecy of the Illinois entomologist, Walsh, recorded 
in the autumn of 1865, to the effect that the insect would 
eventually reach the Atlantic, has been verified sooner than he 
expected. 
In this sketch of its progress it is not to be understood that, 
like a flight of locusts or a herd of buffalo, the hosts of the 
potato-beetle travel onwards, leaving free the districts behind 
them. It appears that American farmers in some States con- 
soled themselves with the belief that it would be so ; but, in 
fact, the pest establishes a permanent colony wherever it goes, 
only the surplus population of the prolific creature moving off 
to new fields ; and notwithstanding the energy with which it has 
been combated it has in no place yet been entirely eradicated. 
It is reported to have been more numerous in Missouri in 1871 
than in any previous year. Some of the details of its migrations 
given by Riley are calculated to impart a lively idea of the strength 
of the impulse which urges it forward, and the difficulties that 
