34 BULLETIN 1iQ, IT. S. DEPARTMENT OP AGRICULTURE. 



One adult emerged in December from eggs laid as late as Septem- 

 ber 25, although the others from this mass of eggs hibernated. In 

 general, it seems that most of the larvae from eggs laid after the 

 middle of September hibernate if they are not killed in the mill, but 

 this depends somewhat on the season, as more will develop in a late 

 fall. All instars of the larvae hibernate. Small first and second 

 instar larvae have been seen as late as the middle of December crawl- 

 ing over the cane tops, and these would hibernate if they found suit- 

 able places. Hibernation is not what may be called complete, since 

 the larvae remain active on warm days and continue to feed to some 

 extent. When infested cane is windrowed in the fall it is often 

 badly damaged by the borers continuing their feeding throughout 

 the winter, destroying many eyes and tunneling the stalks until they 

 become brittle and break with handling. The well-grown larvae con- 

 tinue molting at irregular intervals throughout the winter, but do not 

 increase in size ; in fact, they are even smaller and more flabby in the 

 spring than they are in the fall. The small larvae increase slowly in 

 size and all hibernated larvae are of a very uniform size in the spring. 



PLACES OF HIBERNATION. 



The larvae hibernate in scraps of cane, tops of the cane plant, 

 stalks of large grass, cane stubble, and planted and windrowed cane. 

 Very few are to be found in stubble and grass stalks, however. No 

 larvae have been found in cornstalks during the winter, for these dry 

 out and become unattractive to the moth borer long before cold 

 weather begins. The usual place of hibernation of the closely re- 

 lated species D. zeacoletta, however, is in the taproots of corn. 



The favorite places of hibernation are scraps of cane left after 

 grinding, and windrowed and planted cane. The windrow forms 

 an ideal place for hibernation, the larvae being well protected by the 

 earth and the quantity of leaves covering the stalks. 



EMERGENCE FROM HIBERNATION. 



The hibernating larvae pupate in the spring and emerge as moths 

 when the cane is from a few inches to a foot or more in height. 

 Though planted cane is covered with earth, this is often washed away 

 by a heavy rain, exposing or partially exposing the seed cane. Moths 

 have been found to emerge from cane under one-half inch of packed 

 soil so that it is often possible for them to emerge from planted cane. 

 There is of course no obstacle to their emergence from grass or cane 

 stubble. 



The times of emergence from planted cane under observation were 

 May 7, May 21, and June 1, 1914, and the earliest emergence in the 

 insectary was on May 8. A first-instar larva, however, was collected 

 in the field as early as May 5, indicating that the parent moth must 

 have emerged during the last few days of April. 



