THE SUGAR-CANE MOTH BORER. 



21 



of the egg stage at the prevailing temperatures during the different 

 months is shown in Table III and is graphically illustrated in fig- 

 ure 6. 



Table III. — RelationsJiip of mean temperature to the developmental period 

 of the sugar-cane moth borer in the egg stage. 



Period. 



Average 

 mean tem- 

 perature. 



Number of 

 records. 



Period. 



Average 

 mean tem- 

 perature. 



Number of 

 records. 



Days. 

 4 

 5 

 6 



82.8 

 81.7 

 78.9 



10 

 41 



7 



Days. 

 7 

 8 



9 



o K 



75.2 

 72.1 

 72.4 



1 



1 

 1 



DEVELOPMENT. 



When the eggs are first deposited they are creamy white, and in a 

 field of cane are practically invisible against the light green of the 

 Cane leaves. They gradually darken until they are reddish brown, 

 with the eyes of the embryo showing through as two small black 

 spots. Later the head turns black and the eyes can not be distin- 

 guished, but the segments of the larva are discernible. The head 

 seems to fill the whole egg cavity and gives to the egg mass a bluish- 

 black cast. Just before hatching the larva can be seen moving 

 within the eggshell. v 



HATCHING. 



Hatching usually occurs in the early morning during the summer, 

 and later in the day in cooler weather. Observations indicate that all 

 eggs in a given cluster hatch within a few hours. The larva emerges 

 from the egg by rupturing the upper surface, leaving it torn and 

 ragged but without altering the arrangement or position of the egg 

 in the cluster. The empty eggshells are papery and almost trans- 

 parent, but they show a slight marking under the microscope. The 

 cluster of eggshells adheres to the leaves for some time before being 

 washed away by rains, and is more conspicuous at this period than 

 it is before hatching. 



While no definite record has been maintained of the percentage 

 of eggs which hatch, it is only occasionally that one or two in a clus- 

 ter from a fertilized female fail to produce larvae. Eggs from 

 unfertilized females do not hatch. 



LARVA. 



FOOD HABITS. 



The larvae are active from the time of hatching and almost imme- 

 diately begin their search for food. Those from a single group of 

 eggs congregate in the terminal buds of two or three plants in the 

 immediate vicinity of the place where hatched and begin feeding 



