350 Journal of Agricultural Research voi. iii, no. 4 



Table III . — Length of the egg stage of the three-cornered alfalfa hopper at Greenwood, Miss.; 



host, cowpeas 



Date of oviposition of adults. 



June 30 . 

 Sept. I. . 

 3- 



Date of 

 egg fiatching. 



July 3 



Sept. 8 



Length 

 of egg 

 stage. 



Days. 

 4 

 7 

 5 



Num- 

 ber of 

 eggs. 



Many 

 8 



OVIPOSITION 



In alfalfa. — ^The egg is deposited beneath the epidermis through a 

 long slit made in the stem of alfalfa by the female with her ovipositor. 

 This slit is often several times the length of the egg. Measurements of a 

 large number of slits displayed a variation in length of from 0.75 to 2.25 

 mm. The egg is placed either just below or to one side of this puncture, 

 and occasionally, instead of being just under the epidermis, an egg may 

 be found shoved deep within the plant tissues, even to the center of the 

 stem or beyond. Usually only one egg is deposited through a single 

 opening, but sometimes two or more are placed together. Quite often, 

 however, a great many sUts are grouped side by side and the eggs laid 

 singly but giving the appearance of having been bunched through the 

 same opening. When this is the case, a large scar is made, and the 

 place of oviposition would be quite noticeable if it were not for the fact 

 that it usually occurs back of a sheath leaf or at the surface of the 

 ground, where it is partially hidden. Females have been found with their 

 abdomen extended down the stem of the plant and below the surface 

 of the ground, and subsequently eggs have been found in the stems at 

 such places. It has been observed that eggs are usually laid at night or 

 early in the morning. These observations were made, however, during 

 extremely warm weather; during cold weather the females would prob- 

 ably pick out the warmer part of the day to display their activities and 

 thus avoid the minimum temperature, as they doubtless avoid extreme 

 temperature. 



In COWPEAS. — The method of oviposition in cowpea stems is considerably 

 different from that in alfalfa, the texture of the cowpea plant evidently mak- 

 ing possible the placing of a great many eggs in the stem through one open- 

 ing. Mr. Gibson has found that the eggs are always laid in groups and in his 

 field notes quite aptly refers to these places of o\'iposition as egg pockets. 

 He has observed from i to 1 2 eggs in a pocket. A count of the eggs in six 

 pockets showed respectively 6, 4, 12, 2, 3, and 5 to the pocket. Following 

 oviposition, in about one-third of these pockets a gall formation develops. 

 From their appearance these must be similar to the galls which develop 

 on alfalfa stems following ringing and which are described in the para- 

 graph on alfalfa injury. These naturally give the egg pockets a dis- 

 tinctive and pecuHar appearance. They are often as large as the stem 

 itself, sometimes as much as one-fourth of an inch in diameter, and well 

 show the efforts of the plant toward the heaUng of the injured part. 

 Mr. Gibson thinks that these galls are due to an overproduction of epider- 

 mal cells caused by the physiological stimulus given to the plant by the 

 injury, and states that they are of about the same texture and hardness 



