Page:Popular Science Monthly Volume 7.djvu/727

Rh my seventh report: "Those who have watched the gradual spread of this potato-beetle during the past seventeen or eighteen years from its native Rocky Mountain home to the Atlantic, and who have seen how lakes, instead of hindering its march into Canada, really accelerated that march, can have no doubt that there is. danger of its being carried to Europe. Yet I must repeat the opinion expressed a year ago—and which has been very generally coincided in by all who have any familiarity with the insect's economy—that if it ever gets to Europe it will most likely be carried there in the perfect beetle state on some vessel plying between the two continents. While the beetle, especially in the non-growing season, will live for months without food, the larva would perish in a few days without fresh potato-tops, and would, I believe, starve to death in the midst of a barrel of potatoes, even if it could get there without being crushed; for, while it so voraciously devours the leaves, it will not touch the tubers. The eggs, which are quite soft and easily crushed, could, of course, only be carried over on the haulm or on the living plant; and while there is a bare possibility of the insect's transmission in this way, there is little probability of it, since the plants are not objects of commercial exchange, and the haulm, on account of its liability to rot, is not, so far as I can learn, used to any extent in packing. Besides, potatoes are mostly exported during that part of the year when there are neither eggs, larvæ, nor potato haulm in existence in the United States. There is only one other possible way of transmission, and that is in sufficiently large lumps of earth, either as larva, pupa, or beetle. Now, if American dealers be required to carefully avoid the use of the haulm, and to ship none but clean potatoes, as free from



a, a, eggs: b, b, larva; c, beetle: d, left-wing cover, enlarged, showing marks and punctures; e, leg enlarged. Colors: of egg, pale-yellow; of larva, cream-yellow; of beetle, black, yellow, and brown.

earth as possible, the insect's transmission among the tubers will be rendered impossible; and when such precautions are so easily taken, there can be no advantage in the absolute prohibition of the traffic in American potatoes. As well prohibit traffic in a dozen other commodities, in many of which the insect is as likely to be imported as in potatoes. The course recently adopted by the German Government,