December, '21] sanders and delong: grape berry moth 489 



Areas of infestation are due entirely to the existence in the immedi- 

 ate vicinity of conditions which are suitable to the over-wintering of the 

 pupae, which are usually found in dn*' grape leaves. Conditions favor- 

 able to the collection and aggregation of dry leaves — often blown by the 

 wind — are found in weedy headlands, woodlands, uncultivated fields 

 adjoining strips of uncut weeds along the vineyard, or an abrupt de- 

 pression where snow by drifting can cover the leaves, and thus protect 

 the pupae from freezing. The autumn winds carry the leaves to these 

 grassy and woody areas, where they are held and protected over winter. 



These facts have been verified by placing num.erous grape berry moth 

 pupae respectiveh- in protected and in exposed areas, with the result 

 that those in the open vineyard areas are killed, apparently by freezing 

 and the varying temperatures. 



The amount of infestation of these vineyards ranges from zero to 

 fifty-seven percent as a maximum. Perhaps ten to fifteen rows toward 

 the open vineyard showed a very slight infestation or none whatever. 



An examination of vineyards throughout the entire area has shown 

 this condition to be practically uniform, and when this condition is 

 obser\^ed ^'ear after year it is apparent that the infestation does not 

 continue to s])read during consecutive years, but that the pupae are 

 killed each year, except in the protected zone. vSince the flight of the 

 moths is quite limited, the same areas are reinfested each year from the 

 same source. These \'ineyards under consideration are generally well 

 cultivated, and little o]3portunity exists for vegetation to carry over- 

 wintering -pupae. 



During these observations one vineyard was fotmd containing an al- 

 most uniform infestation of approximately forty percent. On further 

 consideration it was discovered that this vineyard had not been culti- 

 vated for several years, and conditions for overwintering were ideal 

 through cmt the vine\-ard. Abrupt depressions in contour, or swales, 

 occurring in the midst of a cultivated vineyard will furnish the only 

 infestation found in an area of several acres, and the largest percentages 

 of infestation found are caused by a combination of depressions and 

 stretches of abandoned or uncultivated ground, containing a growth of 

 sumacs, brush, or heavy weeds, or a generally wooded area. After a 

 little practice and study of infested areas, these suspicious portions can 

 usually be picked out at a glance over the entire vineyard before clusters 

 are exarrined. 



The direction of the woodland from the vine>-ard seems to make 

 very^ little difference, so long as it adjoins the vine>-ard closely. Slightly 

 more protection, with resulting heavy infestation, seems to be afforded 



