2 CIRCULAR 2 41, U. S. DEPARTMENT OF AGRICULTURE 



The majority of the species are not only very inconspicuous, often 

 being protected by close resemblance to the objects around them, 

 but they are very active, jump quickly when disturbed, and can 

 not be caught without difficulty except in a close-meshed net; when 

 in flight they may very readily be mistaken for other insects except 

 by an especially practiced eye. 



Among many farmers they pass as the " fly," which usually means 

 the Hessian fly {Phytophaga destrwctor Say), and they have been 

 very commonly called the " green bug " by mistaken references to 

 T oxoptercn graminum Rond., which has had such general notice in 

 the daily press. In some localities, notably in the northwestern 

 wheat section, the term " green bug " has apparently been used very 

 commonly for leaf hoppers in the absence of the real Toxoptera. 



NATURE AND EXTENT OF INJURY 



These insects are very widely distributed, affect a variety of cereal 

 and forage crops, and must cause in the aggregate very extensive 

 losses, which are quite generally overlooked or not fully appreciated 

 for various reasons. One reason is that their work is so insidious, 

 and its results, except where the insects occur in unusual numbers, 

 so difficult to appreciate by ordinary observation that it is very 

 likely to pass unnoticed. Another is that injury caused by these 

 insects is very commonly charged to other agencies, either to other 

 insects, to parasitic fungi, to drought, or possibly even to frost, 

 because in many instances the insect itself escapes notice. 



Like other members of the order Hemiptera, such as the squash 

 bug {Anasa tristis DeG.), the chinch bug (Blissus leucopte? v us Say), 

 aphids, scale insects, etc., the leaf hoppers secure their food, and in- 

 cidentally occasion injury, by sucking the juice of the plant. The 

 mouth parts consist of a beak or proboscis, inclosing slender thread- 

 like piercing organs which are thrust into the plant and through 

 which the plant juices are drawn into the stomach. The result of 

 their feeding is a wilting or shriveling of the plant cells that are thus 

 depleted of their contents, sometimes a curling of the leaf or the dis- 

 tortion of the adjacent parts, and in some cases a discoloration of the 

 surface. This sometimes becomes a factor in protecting the insect, 

 especially when the color of the insect and that of the injured plant 

 cells is the same. Probably the most familiar examples of this kind 

 of work are those of the wilting noticed following attacks of the 

 squash bug or the chinch bug, the whitening of grapevine leaves at- 

 tacked by the grape leaf hopper (Erythroneura comes Say), or the 

 coloring and curling of leaves infested by aphids. 



On grasses and grains the attack is most commonly noticed in the 

 form of wilted or discolored blotches on the leaves or stems. It was 

 described by Webster as a combination of punctures and slitting. 

 Sometimes, in bluegrass particularly, it results, as the writer believes 

 (iJ), in the condition known as "silver top," a whitening of the en- 

 tire upper part of stem and head, though this particular condition is 

 in some parts of the country undoubtedly due to attacks of the grass 

 thrips {Thrifts striatus Osb.) 



Another point to be noted is connected with the parasitic fungi 

 that are frequently associated with the leaf hoppers. It seems quite 

 possible that these fungi may be assisted by the leaf hoppers in their 



