28 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



In chapter 13, which is one of the most extended and most important 

 practically, it is clearly sho^ n that the young locusts may be controlled, 

 and by what means, while the way is pointed out how to better control 

 the winged insects. Many valuable devices for destruction are illus- 

 trated, among them one invented by Mr. Eiley, which gave entire satis- 

 iactiou, and will, it is believed, supersede other contrivances as a cheap 

 and practicable means of destruction, applicable at any season, whether 

 the plants or the insects be small or large. In this chapter, also, the 

 necessity of legislation, the relative merits of ditching, plowing, harrow- 

 ing, the use of coal-oil, of various fluids and powders, and of burning are 

 discussed; as also the best means of protecting special plants and trees. 



In chapters 14 and 15 the influence of prairie-fires and of weather 

 on locust-increase is discussed. It is shown that prairie-fires can have 

 but little influence on the multiplication of the insect except when they 

 are judiciously manipulated and controlled as suggested in chapter 13. 

 The effects of frost and of wet weather on the eggs and on the young 

 insects have an important practical bearing, and we have given a series 

 of experiments which prove that the eggs are not greatly influenced 

 either by frost or water. That they should resist intense cold was to be 

 expected, since the species is boreal ; but that they should remain im- 

 pervious to constant soaking, is contrary to the prevailing views hith- 

 erto held on the subject. They are, also, far less susceptible to alter- 

 nate freezing and thawing than was anticipated. The young locusts, on 

 the contrary, perish whenever the temperature falls more than fifteen 

 degrees below freezing-point, while they are very seriously and injuri- 

 ously affected by prolonged wet weather, especially if it be cold in ad- 

 dition. 



The effects that invariably follow severe locust-injury are treated 

 of in chapter 16, and the changes that, in consequence of such injury, 

 take place in the flora and fauna — the increase of some species and de- 

 crease of others— are sometimes very striking. It must also be assur- 

 ing to the people of the West to know that there are good and sufficient 

 reasons why a year of great locust-devastation is apt to be followed by 

 one of locust-immunity and good crops. 



In chapter 17 we have discussed the uses to which locusts may be 

 put, and, not to dilate here on their availability as food for various ani- 

 mals, including man, as fish-bait, or as manure, the chemical analysis 

 given of the dead locusts is quite interesting. The insects furnish a new 

 oil, which we have christened Oaloptine, and a very large percentage of 

 formic acid. Though this acid exists in the ant and some other insects, 

 it is with difficulty obtained in large quantities ; whereas by the action 

 of sulphuric acid upon the locust-juices it passes off with great readi- 

 ness and in remarkable quantity and gravity. The various uses of this 

 acid, whether as a therapeutic, &c., are capable of great and valuable 

 extension where it can be obtained so readily and in such quantity. 



In the two concluding chapters it is clearly shown that locust-ravages 



