THF DIFFERENTIAL LOCrST. 23 



destroyed. It was demonstrated that for such conditions this is one 

 ol" the most satisfactory niethods for quickly checking- the injury over 

 a small area. 



Cauxe of 190]^. ()\(t})reah. — In the summer of 1902 the Brazos River 

 overflowed in a most unusual manner, and again in February, 1903, a 

 smaller overflow occurred. This resulted in large areas throughout 

 the lower Brazos valle\^ remaining- uncultivated in 1903. This hard- 

 packed soil ga\e ideal conditions for oviposition, and the weeds which 

 came in furnished the favorite food of the hoppers, thus making- their 

 I'apid multiplication certain. That an unusual outbreak should occur 

 in the spring- of 1901 was therefore to be expected. Throughout the 

 bottom lands of central Texas this species is always common, and does 

 more or less damage along the edges of the corn and cotton fields; but 

 ordinarily the planters disregard the injury and allow the pest to 

 multiply. Then, when such conditions as those above outlined occur, 

 tlie pest increases verv rapidly and serious injury is widespread, 

 Were the weeds around the edges of the fields dusted with an arsenical 

 whenever grasshoppers are observed to be common, and were uncul- 

 tivated areas plowed during the winter when possible, the num- 

 bers would be so reduced that such outbreaks would not frequently 

 occur. These conditions were exactly similar to those mentioned by 

 Professor Morgan " concerning the outbreak of this species along the 

 Mississippi, after a crevasse had been formed in the levee and a con- 

 sequent overflowing- of the adjacent land had resulted, 



U>>c "f fungous (llseaxes. — Cultures of the fungous diseases with 

 which experiments have been made in recent years as a means of com- 

 bating locusts were secured from several sources. The tubes received 

 from Prof. Lawrence Bruner, of Nebraska, mentioned below, were 

 stated to contain what was prol^abl}- a species of Mucor, Those 

 received from Prof. C P. (rillette, of Colorado, had been sent him by 

 Doctor Edington, of the Bacteriological Institute, Grahamstown, Cape 

 of (xood Hope. Those from the Bureau of Entomology were marked 

 "Culture C," and were also of South African origin, although pre- 

 pared by the Department of Agriculture. These cultures were han- 

 dled according to the directions sent with them,'^ and locusts dipped in 

 the prepared solution were freed where the}^ were most abundant in 

 the lield. Corn meal moistened with the solution was also scattered in 

 these localities. These distributions were made on April 19, at four 

 points, several miles apart. Examinations on April 29 and May 9 failed 

 to reveal any grasshoppers dead from disease, nor did the planters see 

 any later in the season. After May 1 the locusts had been so depleted 



^'1901: Bui. 80, n. s., Div. i:nt., U. S. Dept. Agric, p. .31. 



''See Howard, Yearbook U. S. Dept. Agric. f. 1901, p. 464; and Bruner, Bui. .iS, Div. 

 Ent., U. S. Dept. Agric, p. 50. 



