4 BULLETIN 550, U. S. DEPARTMENT OF AGRICULTURE. 
If the infested berries are trirnnied out of the clusters the loss of their 
weight is total in addition to the cost of trimming. 
While the berry moth is not as generally destructive as the grape 
rootworni or grape leafhopper, it is capable of inflicting greater losses 
than either to a single season's crop, and neither of these pests will 
appear in destructive numbers with such alarming rapidity in a vine- 
yard which has been apparently free from them as will the grape- 
berry moth. When it is present at all in a vineyard it always causes 
a loss in weight and is a constant menace to the grape industry in 
that vicinity. 
SUMMARY OF SEASONAL HISTORY AND HABITS. 1 
Before considering control measures, a summary of the seasonal 
history and habits upon which these measures are based will be given. 
There are two broods of the grape-berry moth that must receive 
economic consideration. The first brood, resulting from the hiber- 
nating generation, is comparatively small, owing to high winter mor- 
tality of the pupae. The earliest recorded emergence of moths is 
May 29 and the latest July 26; however, the bulk of the emergence 
begins between the 10th and the 25th of June, varying with the sea- 
son, and usually is ended within 3 weeks. Within 4 to 6 days after 
emergence the moths (PL I, figs. 4, 5) begin depositing eggs, preferably 
on grape berries. Incubation requires about 6 days. Thus the hatch- 
ing period of large numbers of larvae begins from June 20 to July 5, 
depending upon the season, and continues for about 3 weeks. 
The beginning of this period is almost coincident with the falling of 
the grape blossoms and the setting of the fruit. The larval feeding 
period averages 23 days, after which the larvae (PL I, fig. 1) spin 
cocoons in leaves on the vine, and in an average of 13 days emerge as 
moths. Some pupae (PL I, fig. 3), however, do not transform at this 
time but remain in the cocoon (PL I, fi.g. 2) until the following spring. 
The earliest recorded emergence of summer-brood moths is July 12 
and the latest is after the middle of September. A heavy emergence 
of moths begins in a normal season in the latter part of July, and in 
backward seasons may continue as late as the earlier part of Septem- 
ber. Although the second brood is only a partial one, it is by far the 
more numerous and destructive. It may escape serious attention 
from the # vineyardists until shortly before harvest, when the well- 
grown larvae begin to leave the berries they first attacked and to 
enter others. 
The development of this brood is slower than that of the first. In 
a normal season the larvae are cocooning in large numbers by the lat- 
ter part of September and by the middle of October most of them 
1 This summary is based on the life-history studies of the grape-berry moth by Johnson and Hammar 
and studies by the writer and his associates, the details of which have not yet been published. 
