358 Journal of Agricultural Research voi.iii, N0.4 



feeders, and, being more sedentary, their feeding is more nearly restricted 

 to a definite area or ring, and with this concentration of work the effect on 

 the plant is more pronounced. 



The gall following the girdling of the stem, shown in Plate XLIII, figure 

 6, h, is also quite detrimental to the plant. It is an effort on the part of 

 the plant to mend the injury. There is always a thickened area in the 

 epidermis both above and below the ring, and often this takes peculiar 

 shapes. At one time the swellings will take the shape of globules larger 

 in diameter than the stem itself ; at other times a rootlike projection, often 

 half an inch in length, will shoot out; and nearly always, sooner or later, 

 under the pressure of wind or other external influence, the plant will 

 break off and be of little value as food. The more tender stems are 

 always chosen by the insects in preference to the older and more fibrous 

 ones, and thus the maximum of food is found with the least labor. During 

 cool days and cooler weather the feeding is done close to the ground ; dur- 

 ing warmer weather the species feeds high up on the plant and in the 

 extreme heat of the summer it feeds on the shady side of the stem. 



INJURY TO THE CROP 



The damage to alfalfa, while not as serious as that caused by some 

 other alfalfa pests, is considerable. To the casual observer it does not 

 appear to be so heavy, chiefly because nothing is seen to be devoured, as 

 in the case of lepidopterous lar\^ae; and yet, because of the great numbers 

 appearing in alfalfa in the late summer months, farmers have often com- 

 plained of the hoppers in their fields and have imagined that they were 

 doing damage which in reality was due to larv'se of the yellow alfalfa 

 butterfly {Eurymus eurytheme). As has been noted, during the latter 

 part of August and continuing through September that species, as well as 

 a jassid, Empoasca mali Le B., attains immense numbers and flies in great 

 swarms before one in an alfalfa field. At this period of the year the alfalfa 

 is fibrous, lacks succulency, and the growth is neither heavy nor thrifty. 

 The hot weather is usually blamed for all this, but the fact is that a con- 

 siderable percentage of the injury is due to the action of these insects. 

 With dozens of hoppers feeding upon every stem and hundreds upon every 

 plant, all sucking the plant juices, checking plant growth, and girdling 

 many stems, causing them to shrivel and possibly to die or even break off, 

 It is no wonder that the alfalfa looks sickly and is of slow growth during 

 these months. On September 10, 1912, the writer made the following 

 note: 



To-day by motor cycle I went to Chandler, Ariz., to inspect an alfalfa field on Mr. 

 Childs's ranch, which was reported as being "killed off" by insects. Upon reaching 

 the field, I found that the alfalfa was in bad condition. The stems were so scarred 

 from the feeding punctures of Slictocephala fesiina and jassids that they presented a 

 stick)-, sickly appearance, and the stems were dry and shnmken so as to be pliable to 

 the touch and not solid and rigid, iis they should be. A great many fields to the south- 

 east of Tempe show this damage to a greater or less extent. 



From the notes of Mr. T. Scott Wilson I copy the following: 



Tempe, Ariz., September 26, 1913. Stictocephala are very numerous now around 

 Tempe. They are doing a great amovmt of damage, more than at any time this year. 

 Many alfalfa stalks are completely girdled near the groimd and will break off very 

 easily at this ring where the bug has sucked the juice from the stalk. Some have a 

 great many small spots scattered along the stalk where the insects have fed. Other 

 stalks have new branches starting up just below the girdled place, and some are green 

 below this ring and yellow above it. There isn't any doubt (in the writer's mind) thai 



