25 



(3) The life cycle covers about one year. About three weeks are 

 required for the egg state; about nine months for development from 

 hatching to the adult stage; and over two months for the preoviposi- 

 tion period. 



(4) Although the mole cricket has many natural enemies, particu- 

 larly among the native birds, it is not held in check by them. 



(5) With the exception of a nematode, no parasitic enemies of the 

 changa are known to occur in Porto Rico. 



(6) During the fall months the changa flies in large numbers on 

 damp, overcast evenings. The greater proportion of changas at- 

 tracted to lighted areas are females. Flooding is of value wherever 

 the location of fields makes water easily available. 



(7) Xaphthalin and sulphur are the only repellents found to be of 

 any value, and even they are only partially effective. 



(8) Sugar cane is protected from the changa by planting it in a 

 perpendicular or a slanting position. Hilling up plants greatly re- 

 duces changa injury in gardens. 



(9) The use of poison baits, together with clean cultivation of 

 the area to be planted, is recommended. A mixture of cheap flour 

 and Paris green is particularly acceptable to the changa. 



ACKNOWLEDGMENTS. 



The writer wishes to make acknowledgment to Mr. Thomas H. 

 Jones, formerly of the Sugar Producers' Experiment Station at 

 Rio Piedras, for his suggestions at the commencement of the work 

 and for reading over the manuscript; to Mr. S. S. Grossman, for- 

 merly of the board of commissioners of agriculture, for his valuable 

 suggestions; to Mr. A. N. Caudell, of the United States Bureau of 

 Entomology, for his help on the systematic side of the subject and 

 for calling the writer's attention to recent literature; to Mr. E. G. 

 Smyth and Mr. G. X. Wolcott, of the Insular Experiment Station, 

 for continuing the breeding work in the writer's absence; and to 

 his wife, Mary P. Van Zwaluwenburg, for her painstaking work in 

 the preparation of drawings. The author also expresses his appre- 

 ciation of the help rendered by his numerous correspondents in de- 

 termining the range of the mole cricket. 



BIBLIOGRAPHY. 



(1) AUDINET-SEKVILLE, J. G. 



1839. Histoire Naturelle des Ingectes. Orthopteres, p. 309. Paris. Not 

 seen by writer. 



(2) BARRETT, O. W. 



1902. The changa, or mole cricket (Scapteriscus didactylus), in Porto 

 Rico, Porto Rico Sta. Bui. 2, pp. 19, fig. 1. 



