HARD WICK E'S SC I E N C E-GO S S IP. 



15 



A NEW ENEMY. 



I WISH to say a fe<v words about an enemy which 

 threatens to lay waste one of Europe's most 

 valued esculents, the potato. Eor a long time 

 North America has had to contend against two 

 foes, which devoured the early shoots and leaves of 

 the potato, and thus destroyed the hopes of the 

 farmer and gardener. These were beetles belonging 

 to the same family as tlie Blister-fly, and named 

 Lytta atrafa (or vittatci) and Cantharis viniaria. 

 They can be kept within bounds ; but of late a 

 third beetle has appeared among us which really 



Fig. 17. Colorado Potato Beetle iu diCferent stages, from egg to perfect insects 



threatens to drive the potato out of cultivation 

 altogether. It bears the name of the Colorado 

 Potato-beetle [Bonjphoru decern -punctata) ; and 

 should it once reach the Atlantic coast, and be 

 carried unobserved across the ocean, tiien— woe to 

 the potato-grower of the old country ! 



A man must witness the myriad legions of this 

 insect, and the ravages of its never-tiring larvae, in 

 order to form an idea of the terrible danger with 

 which Europe is threatened. For myself, judging 

 from the tenacity of life exhibited both in its larval 

 and perfect condition, I have not a doubt that it 

 will soon overstep the bounds of North America, 

 and make a home for itself in other lauds. 



Its true domicile is in the Ilocky Mountains, 

 where it feeds on a species of wild potato, Solatium 

 rostratum (or Carolinianee) . No sooner, however, 

 had the edible potato [Solanum tuberosum) been 

 planted by settlers at the foot of these mountains, 

 than Doryphora attacked it greedily; the more 

 largely its cultivation extended westward, the faster 

 did its insect foe travel in an easterly direction, and 

 scatter itself over the land. In the year 1859 it 

 was located one hundred miles west of Omaha city, 

 in Nebraska; in 1S61 it showed itself in Iowa; in 



1SG5, not only had it begun to devastate Missouri, 

 but it had crossed the Mississippi in Illinois, every- 

 where leaving behind it flourishing colonies. In 

 1868 Indiana was visited ; in 1870 Ohio and the 

 confines of Canada were reached, also portions of 

 Pennsylvania and New York ; and its entrance into 

 Massachusetts was notified. During the year 1871 

 a great army of these beetles covered the river 

 Detroit in Michigan, crossed Lake Erie on floating 

 leaves and similar convenient rafts, and in a very 

 short time took possession of the country between 

 St. Clair and Niagara rivers. Having got thus far, 

 in spite of all efforts to stay their progress, there 

 is every reason to believe that be- 

 fore long we shall hear of them as 

 swarming in the streets of New 

 York and Boston (as they already 

 swarm in the city of St. Louis), 

 and then their passage across the 

 Atlantic is a mere matter of time. 

 Moreover, the beetle in its different 

 stages is so entirely unaffected by 

 the extremes of heat and cold, of 

 wet and dry, which it has met with 

 here, that I have no doubt it will 

 care as little for the changes of 

 climate which occur in the temper- 

 ate zone of Europe, and, once set- 

 tled, will quickly become natural- 

 ized. 



The devastations of the Colorado 

 Beetle are all tlie greater, from 

 the fact of its propagating itself 

 with extraordinary rapidity, several 

 broods following each other in the course of the year. 

 Thefirstbatchof infant larvse appears towards the end 

 of May, or, if the weather be mild, of April. In fact 

 scarcely has the potato plant shown itself above the 

 ground, before the insect, which has been hyber- 

 nating during the winter, also wakes to life. The 

 female loses no time in depositing from seven 

 hundred to twelve hundred eggs, in clusters of 

 twelve or thirteen, on the underside of a leaf. 

 Within five or six days, according to the state of 

 the weather, the larvse escape from the egg, and 

 begin their work of devastation, which goes on for 

 some seventeen days, when the little creatures retire 

 below the soil, in order to undergo the pupal con- 

 dition. After a delay of ten or fourteen days, the 

 perfect insect comes into being, and the business of 

 egg-laying commences anew. In this way, accord- 

 ing to recent observations, three broods follow each 

 other; the last, as just stated, wintering below the 

 surface of the ground. No description can do justice 

 to the marvellous voracity of this insect, especially 

 in its larval state. When once a field of potatoes 

 has been attacked, all hope of a harvest must be 

 given up ; in a very few days it is changed into an 

 arid waste — a mere mass of dried-up stalks. 



