8 
BULLETIN 419, U. S. DEPARTMENT OF AGRICULTURE. 
tuted the food of a single larva throughout its life. On the other 
hand, a single large leaf may be 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 
full-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 hi 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, which 
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. 
