grate to the adjacent fields nearly at the same time, their coming all at 

 once, or within a short time of each other, would very naturally attract 

 attention. Moreover, it is very evident that they appeared in greater 

 numbers the present season than they do in ordinary seasons, since none 

 of their eggs were destroyed by being covered with water for too long 

 a time. 



As stated above, the locusts left the grain fields this season a few 

 weeks after the latter had been harvested, there being no green food 

 for them to obtain in these fields ; but it is quite probable that, as last 

 season was a veiy wet one, there may have been green weeds in the 

 grain fields as late in the season as the locusts deposit their eggs, and 

 if such was in reality the case, then we may suppose that many of the 

 locusts deposited their eggs in the fields last autumn. This would ac- 

 count for the fact that the locusts were most numerous the present 

 season on those fields which had not been plowed for over one year. 



From the above facts it would appear that whenever there is a very 

 dry winter and spring in the San Joaquin Valley there will be an abun- 

 dance of locust's in that valley during the following summer ; but when 

 there is an abundance of rain during the winter and spring months 

 there will not be an unusual number of locusts during the following 

 summer. 



In the latter part of July I saw several pairs of the Ash-colored Locust 

 (M. cinereus] united in coition, but up to the time that I left this valley 

 the first week in August I did not see a single pair of the Devastating 

 Locust thus united. 



THE DIFFERENTIAL LOCUST. 



The Differential Locust (Caloptenux differ entiaUx Thomas) was only 

 about one twenty-fifth as numerous as the Devastating Locust. These 

 two species and the Ash colored Locust were the only Spine breasted 

 Locusts that appeared in destructive numbers in the San Joaquin Valley 

 the present season. The only other species of Spine breasted Locusts 

 that I took in that valley are the Acridium shoshone Thomas ^ the Hes- 

 perolettix viridis (Thomas), and the Paroxya (near atlantica Sc.). 



When I first came to this valley, early in June, the Differential Locust 

 was mostly in the wingless state, there being only about one winged speci- 

 men to ten wingless ones ; by the last week in July the greater number 

 of them had acquired wings. On the 23d of June I saw the first pair 

 united in coition, but the majority of them did not pair until about three 

 weeks later. After coition, and before the eggs are deposited, the 

 abdomen of the female increases very much in size. 



The first egg-mass which I saw this species deposit was deposited on 

 the 23d of July. The location chosen was a shaded place on the north 

 side of a row of trees and in a sandy soil. A basin-like hole had been 

 dug in the ground at the base of an ornamental tree, and had been filled 

 with water a day or so previously, for the purpose of irrigating the tree. 

 The female locust had worked her abdomen into the ground on the 

 outer edge of this basin. I first discovered her in this position at about 

 3 o'clock in the afternoon, and at 15 minutes past 4 o'clock she had com- 

 pleted depositing an egg-mass and walked away. 



This egg mass is about three -fourths of an inch long, slightly curved, 

 and a little less in diameter than an ordinary lead pencil. The space 

 between the uppermost eggs and the surface of the surrounding earth 

 was filled in with a frothy matter. When freshly deposited the egg- 

 mass is of a pale bluish color. 



