CONTROL OF THE GRAPE-BERRY MOTH. 5 



have left the berries. However, in the very late autumn of 1915 the 

 majority of the larvae did not leave the berries until after October 25. 

 Winter is passed in a cocoon, usually spun in a decayed grape leaf 

 under the trellis. (PL III, fig. 2.) 



FEEDING HABITS OF LARVAE. 



The very few early larvae which hatch before the grape blossoms 

 fall feed in the blossom cluster. But most of them, coming after the 

 grapes are set, eat at once into the berry, causing the characteristic 

 purple spotting and cracking of grape berries. 



The point of entrance may be anywhere on the surface of the 

 grape berry, but before the berries touch, about half of the larvae 

 enter around the stem attachment. Of 500 infested berries counted 

 on July 14, 1916, about 12 days after setting of grapes, 266 were 

 entered at the stem end and the other 234 from other parts of the 

 grape berry. After the grape berries reach the stage of growth 

 where they begin touching, the point of contact becomes the most 

 common place of entrance. 



The early larvae, which hatch when the grape berries are still small, 

 destroy many more berries than do larvae which hatch after the grapes 

 are larger. ' 



FLIGHT OF MOTHS. 



The distance which moths of this species may fly in large numbers 

 is uncertain, but as a rule the spread of infestation is slow. In one 

 instance serious infestation advanced from a heavily infested vine- 

 yard into an adjacent young vineyard not more than 100 or 120 feet 

 distant. In this vineyard there could have been no previous infes- 

 tation, as it had just come into bearing. Some infested berries were 

 found 350 feet from the older vineyard, but very few. On the other 

 hand, the following season a vineyard about 1,100 feet wide, newly in 

 bearing, was traversed and infested heavily by a single generation. 

 The spreading of infestation probably is much influenced by weather 

 conditions at the time of the flight of moths. While it may be slow 

 ordinarily, no vineyard is immune from rapid infestation in a vicinity 

 where the berry moth is present. 



HISTORY OF CONTROL METHODS. 



Measures to control the grape-berry moth, since its appearance as 

 an economic pest, have developed gradually from many sources. 

 The first considerable advance toward a solution of the problem, 

 however, was made by the biological and systematic studies of 

 Slingerland (9) 1 and Kearfott (8) in which they definitely de- 

 termined the limits of the species and the fact that the grape was 

 its only food plant; and by Slingerland's field experiments, which 



1 References is made by number to " Literature cited," p. 42. 



