The Locust Plague in America

Abstract

THE greater part of this treatise has already appeared in the Entomological Reports published annually for some years past by Mr. Riley, as State Entomologist for Missouri, in which the information was given piecemeal from time to time as it was acquired. The whole is now brought together in a connected and systematic form, and we have in it a very complete and valuable treatise on the different kinds of locusts, whether species or varieties, which have proved destructive in North America. Ever since the discovery and colonisation of that continent the new settlements have been from time to time subject more or less to scarcities resulting from the invasions or migrations of these insects. These have gradually, however, become scarcer and scarcer, and confined more and more to the interior as the insects retreated before the advancing wave of civilisation and cultivation, until now their ravages do not extend eastwards beyond the 16th or 17th degree of longitude west of Washington; in other words, the regions lying to the east of the Mississippi are now nearly free from them, and it is only in those lying to the west of that river that their propagation and migrations take place on such a scale as seriously to affect the property and prosperity of the settlers. It is not that the species originally inhabiting the eastern coast have been gradually pushed back to the interior, but that the species peculiar to it have been reduced in number in the cultivated districts, and their rôle has been successively taken up by other species lying more inland as civilisation has gradually advanced. The species on which that mission has now devolved are two or three that have their home and permanent breeding-place in the Rocky Mountains—we say permanent in contradistinction to temporary breeding-place, because when they make their migrations, they often rest and breed at its furthest limit, the brood returning in the following year to the country from which their parents came, although not necessarily by the same route. The route by which they have hitherto invaded the countries to the east of their proper home in the Rocky Mountains has been from north-west to south-east. That by which the fresh-bred swarms sprung from the invaders have made their way back again next year, has been from south-east to north-west, but not absolutely in the same line by which their parents came, but either parallel to it or slightly divergent. Their course of invasion has been carefully traced for many years by Mr. Riley and others, and the fact of their return on their footsteps in this way is beyond question; but it is also beyond doubt that the new brood does not go back so strong or so numerous as their parents came. Their constitution appears to be sapped by the change of climate or condition of life; they are feeble and infested by parasites, so that a large proportion of them die a natural death—a consideration which doubtless explains why the vast swarms which have passed from one country to another in all ages and in all quarters of the globe, seem never to have made good a permanent footing in the country they have invaded; at all events never in numbers at all corresponding to the force of the intruders. This is no doubt but small consolation to settlers living on the borders of a locust-stricken land, but it is better than none—they would be still worse off if the locusts were to remain as a permanent incubus instead of only coming occasionally as a ravaging horde.

The Locust Plague in the United States; being more particularly a Treatise on the Rocky Mountain Locust, or so-called Grasshopper, as it occurs East of the Rocky Mountains, with Practical Recommendations for its Destruction.

By Charles V. Riley, State Entomologist of Missouri, &c. With 45 Illustrations. (Chicago: Rand, McNally, and Co., 1877.)