﻿OF THE STATE ENTOMOLOGIST. 39 



of the winter will hardly affect it, except in reducing the number of 

 possible annual broods, and consequently its power of multiplication. 

 The state of dormancy once entered into may continue a month or 

 two, more or less, without seriously affecting most insects. We may 

 expect, therefore, to see it push to the northernmost limit of the potato- 

 growing portion of the country — a limit which it has already well nigh 

 reached. 



The question whether it will extend farther westward and reach 

 the Pacific, is a more interesting one. There is the best reason for 

 believing that the Rocky Mountains furnish an impassable barrier to 

 it, as they do to so many other insects. It has already been shown 

 (Rep. 7, p. 2) how potatoes in the mountains were for years less affected 

 than were those of the Mississippi Valley; but that in 187J: the insect 

 proved quite injurious to those of the mountain region of Colorado. 

 The fact is well established that it has not reached more than three or 

 four miles into the mountains, or to about the middle elevations — say 

 8.000 feet above the sea level. The reason is that the atmosphere 

 above that level is so dry and attenuated that, taken in connection 

 with the cool nights, the eggs, or the larvae that succeed in hatching 

 from them, shrivel and dry up. We have here, therefore, a physical 

 barrier to its further westward progress, and the beetle is no more 

 likely to reach California without man's direct assistance and carriage 

 than it is to cross the Atlantic Ocean without the same means. 

 Whether it could thrive on the Pacific Coast, where the summers are 

 so dry, is another question ; but I fear it would hold its own, in many 

 portions, if once introduced. In this connection it will be well to 

 state that geographical races of Doryphora \0-lineata^ differing in no 

 very important characters from the typical northern specimens, occur 

 in S. Texas, New Mexico, Arizona and Mexico, though they seem to 

 have no more acquired the potato-feeding habit than the D. juncta 

 has done. 



now IT HAS AFFECTED THK PRICE OF POTATOES. 



During the earlier years of the insect's devastations in the Missis- 

 sippi Valley, it materially affected the price of potatoes, not only by 

 its direct ravages, but by discouraging farmers from attempting to 

 cultivate the crop on an extensive scale. In 1873 the price reached 

 the high figure of $2.00 per bushel (wholesale) in the St. Louis market, 

 and many a family had to forego the luxury of a product which a few 

 years before had been one of the cheapest of the farm, and so abun- 

 dant as to enter largely into the feed of all kinds of stock. At the 

 present time, with the improved methods of fighting the enemy, there 

 is no longer the same dread of it in the Western States that formerly 



