LAWSON : KANSAS CICADELLID^. 13 



The damage done by reducing yields may be divided into 

 four heads: 



1. Damage to forage crops and pastures. 



2. Damage to grains. 



3. Damage to orchards, vineyards and gardens. 



4. Damage to shade trees and ornamental plants. 



The total value of our forage crops would be hard to esti- 

 mate and also to overestimate, for under this head would come 

 the leguminous crops such as the clovers and alfalfa, the hay 

 crops both wild and cultivated, and the immense amount of 

 food furnished by pastures. The following table, copied from 

 Hitchcock's textbook on grasses, will give some idea of the 

 tremendous importance of such crops in a single year, 1909 : 



Produotioii Value 



\cres. (Tons). ( I)o)Imi-s'i . 



Timothy alone 14,686,393 17,985,420 188,082,895 



Timothy and clover mixed 19,542,382 24,748,555 257,280,330 



Clover alone 2,443,263 3,158,324 29,334.356 



Alfalfa 4,707,146 11,859,881 93,103,998 



Millet or Hungarian grass 1,117.769 1,546,533 11,145,226 



Other tame or cultivated grasses, 4,218,957 4,166,772 44,408,775 



Wild, salt or prairie grasses 17,186,522 18,383,574 91,026,169 



Grains cut green 4,324,878 5,367,292 61,686,131 



Coarse forage 4,034,432 9,982,305 46,753,262 



Thus we find nearly 75 million acres of land devoted to pro- 

 ducing forage crops, yielding annually nearly one hundred 

 million tons valued at over 800 millions of dollars. For to- 

 day all these figures, especially that of the value, must be de- 

 cidedly low. Then too they do not include the immense value 

 of the forage produced by the millions of acres of pastures. 



The amount of loss to such crops due to insects is hard to 

 estimate and it is still more difficult to correctly determine the 

 amount of injury due to one group of insects when there are 

 many different kinds infesting the crop. But we are perhaps 

 safe in saying that by far the most numerous and widespread 

 of the insects affecting such crops are the leaf hoppers, and 

 that a goodly share of the shrinkage in such crops, due to 

 insect pests, is due normally to these forms. It will require 

 much more accurate and persistent experimenting than has 

 yet been done to enable us to be at all dogmatic about the 

 exact relation of the Cicadellidas to the forage crops, but yet, 

 thanks largely to Professor Osborn's work, we can safely 

 accept some facts, while holding others in abeyance till further 

 work is done. 



