8 



BULLETIN 4:19;, U. S. DEPARTMENT OF AGEICULTUEE. 



tuted the food of a single larva throughout its life. On the other 

 hand, a single large leaf may he the object of attack of more than one 

 larva, seven having been counted under field conditions. 



In the latitude of Washington, and perhaps in most of the Northern 

 States, there are two generations of the grape leaf-folder each year. 

 In the Southern States it is thought that there may be three or 

 more generations annually. 



The majority of first-brood larvae pupate during July, the average 

 length of time passed in the larval stage being about four weeks. The 

 fidl-grown larvae leave their shelters and drop to the ground, where 

 they transform among fallen leaves, trash, etc. In exceptional cases 

 a larva may web several leaves together on the grapevine and pupate 



within this shelter, or 

 ^ it may even pupate 

 within the folded leaf 

 where it has fed. 



During the latter 

 part of July and 

 throughout August 

 the moths are again 

 flying and depositing 

 eggs, from which will 

 hatch the larvae of 

 the second brood. 



Compared to the 

 number of larvae that 

 appear in the second 

 brood, those of the 

 first are quite insignificant, and it is through this great increase in 

 numbers that the injury becomes serious in late summer and fall. 



These larvae of the second brood begin to pupate in September in 

 the latitude of Washington, and by the middle of October few, if 

 any, are to be found in the leaves. The pupae of this brood are also 

 to be found among the dead leaves on the ground, and it is in this 

 stage that they pass the winter. 



Fig. 3.— Larva of grape leaf-folder under its web on grape leaf, wliich 

 has been spread open. Much enlarged. (Original.) 



NATURAL ENEMIES. 



The larvae and pupae of Desmiafuneralis are preyed upon by a num- 

 ber of hymenopterous and dipterous parasites. These natural enemies 

 help materially in keeping down the numbers of the pest, and are, 

 together with other factors, responsible for the greatly diminished 

 numbers of the overwintered pupae, and consequently of the first brood 

 of larvae in the spring. 



