2 FIELD OBSERVATIONS ON SUGAR-CANE INSECTS. 



examined, and sometimes it seemed ])referable to examine 75 stalks 

 in each of two fields rather than to concentrate the work on one field. 

 The number of fields examined in one vicinity varied from one to four, 

 depending on the amount of time at the disposal of the inspector. 

 The infestation of the moth borer seems to be fairly uniform in a given 

 district, and it is beheved that the results obtained give a good idea 

 of the relative infestation by the insect. 



Examinations were made from May 24 to November 26, 1912. It 

 was difficult to determine the full infestation of the moth borer during 

 the first part of tlie season, however, and in the table which follows 

 the results for October and November only are given. Early in the 

 season the cane can hardly be carefully examined without damaging 

 the plant, and the infestation of the moth borer is then small com- 

 pared to the infestation that may be expected later. The dates of 

 inspection are given in the table because the infestation seems nor- 

 mally to increase until the cane is cut. Thus the infestation of a 

 certain field would probably be greater on November 1 than on 

 October 1. Comparisons of the different percentages can be made 

 more accuratel}^ if tliis is kept in mind. 



Table showing the percentage of sugar cane infested by the moth borer at various places 

 in the Southern States in 1912. 



The foregoing table indicates that the infestation of the moth borer 

 varies from 99 per cent (or practically all canes infested) at a point 

 in the Rio Grande Valley in Texas to per cent (or no canes infested) 

 at places in northern Louisiana, Alabama, and JVIississippi, and even 

 at Sugar Land and Victoria, Tex. At Victoria our notes are corrobo- 

 rated by Mr. J. D. Mitchell, a resident agent of the Bureau of Ento- 

 mology, and planters near there are entirely unfamiliar with the moth 



[Oir. 171] 



