246 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



were noted from January to March, and another was evident in April 

 in certain districts. Thus there were at least five and perhaps six 

 generations from December to April. 



The abnormal fermentation of the soil, which was so pronounced 

 as to sour the air in the fields, not only stopped the activity of the 

 plants but probably killed a large part of the enemies of the cater- 

 pillar. The common Encelatoria australis, one of the Compsilurine 

 flies, was found commonly in the fields in April and was reared from 

 the caterpillars. It does not go into the soil for pupation as a rule, 

 while other muscoid species that probably attack the caterpillar enter 

 the soil to pupate and were uncommon in the fields. Every detail of 

 the complex of unusual conditions appears to have been exactly in 

 favor of the caterpillar. The moths appear to have been carried to a 

 considerable extent from one irrigated valley to another by the strong 

 southeast wind already mentioned. The southernmost districts were 

 the first to show decided injury, beginning early in January. The 

 injury spread northward in a wave of increasing intensity during the 

 next two months, while the greatest injury in some of the southern- 

 most districts came later in April. 



In the Casma valley, which is in the northern edge of the region of 

 greatest defoliation, the caterpillar was noted as alarmingly abundant 

 in isolated spots in the upper districts about the end of January. 

 Fifteen days later there was a general infestation by spots, and active 

 general defoliation began about the last of February and was com- 

 pleted about March 5. In the lower districts of the Casma valley, 

 unusual multiplication of the caterpillar was not noted till February 9, 

 and defoliation did not become complete. From March 5 to 21 there 

 was practically not a leaf or sign of growth in the defoliated areas. 



No arsenates were on hand in any quantity, and by the time the 

 planters awoke generally to the importance of the outbreak, the cater- 

 pillar was so far advanced that little could have been done had poi- 

 sons been available. The American Upland is the variety universally 

 cultivated in all the districts in question, the yield being from 460 to 

 500 pounds lint cotton per acre. Some of the largest plantations in 

 these valleys lost heavily by the caterpillar, one estimating its loss at 

 £12,000. The Casma valley had about 3,500 to 4,000 acres in cotton, 

 the loss by the caterpillar being over £20,000 on this acreage. The 

 entire loss by the caterpillar in the Chancay to Casma districts, from 

 January to April, is estimated at something over £70,000. 



