354 



Journal of Agricultural Research 



Vol. III. No. 4 



It is to be noted that in the third stage the 21 -day maximum was 

 observed in only one specimen, and this seems to be an extreme one, 

 as the next highest maximum was only 10 days. 



Looking at the Greenwood (Miss.) records for the nymphal periods, 

 one finds not nearly as much variation between these and the records for 

 Tempe, Ariz., as was exhibited in the incubation records for the two 

 places. The nymphal period required from 22 to 30 days for completion 

 with cowpeas as a host plant. 



Table V. — Length of nymphal period of the three-cornered alfalfa hopper at Green- 



■wood. Miss. 



Date of emergence from egg. 



Julys- 



Aug. 8. 

 Sept. 8 



Date of fast molt. 



Aug. 3. 

 Sept. 3. 



30 

 Oct. 6. 



Length of 

 period. 



Days. 



30 

 26 



22 

 28 



HABITS OF THE NYMPHS 



Hatching. — ^The egg in hatching splits across one end and about one- 

 fifth of the way down one side, and the nymph wriggles its way out. Its 

 legs spread and in a few minutes it begins feeding. Two specimens were 

 timed and one required 18 and the other 28 minutes to complete the 

 process. 



Protection. — If left alone, the first-stage nymphs are very quiet and 

 slow of movement, feeding in almost the same spot for days. As soon as 

 approached by any object, they hastily place themselves on the other side 

 of theplant and out of harm's way. The oldernymphs are quite active and 

 along with the younger exhibit a peculiar protective habit. If approached 

 by an enemy or a supposed enemy, as the point of a camel's-hair brush, they 

 throw the point of the abdomen toward the object and voiding a large 

 bubble of watery excrement, explode it in the face of the enemy and then 

 hastily move to the other side of the plant. In teasing a nymph in order 

 to get it to display this habit the writer has cautiously moved the point 

 of a lead pencil at the head of the nymph, and in trying to project the 

 anal segment towards the pencil the nymph would nearly lose its footing. 

 This habit is probably of considerable benefit as a protection and along 

 with the homy appearance of the nymph doubtless furnishes immunity 

 from many a hungry foe. 



Molting. — The process of molting is interesting. As observed in two 

 specimens it required 48 minutes for the one and 32 minutes for the other. 

 Most of this time was occupied in getting a spUt started in the thorax. 

 After the split was once started, the actual time required for the insects 

 to wriggle out was 2 and 5 minutes, respectively. The description of the 

 action is taken from the writer's original notes, made on March 20, 1912. 



Just previous to molting, the skin becomes very tight and rigid, owing, of course, 

 to pressure from within. The abdomen appears like an overinflated football bladder. 

 The specimen, becoming quiet, forces its proboscis firmly into the stem, and using 

 this as a pivot, with its legs to assist, it begins various body movements, such as 

 straightening out its head, waving its abdomen up and down and, alternately with 

 this, hunching the thorax upward, then resting a brief moment, whereupon the same 



