36 



BULLETIN" 911, U. S. DEPARTMENT OF AGRICULTURE. 



on November 5, and at Kelleys Island, Ohio, on November 7, live 

 larvae were plentiful in the grapes and no case was found where the 

 larva? had been killed by the freeze. In the insectary at Sandusky 

 after a minimum temperature of 23° F. had been recorded, larva? con- 

 tinued to leave the grapes and spin cocoons. Live larva? persisted 

 in the insectary on December 3, 1917, after a minimum temperature 

 of 17° F. had been recorded. 



LARVA SPINNING ITS COCOON. 



On July 9, 1916, a first-brood larva was observed making its 

 cocoon. When first observed the characteristic flap had been cut 

 in the leaf but was not folded. The process observed was the turning 

 over and tying down of the flap. The larva began at one end and by 

 rapid movements of its head from the free edge of the flap to its 

 place of attachment it gradually drew the flap over, the body of the 

 larva resting on the flap, and eventually inclosed in it. The entire 

 process observed occupied 35 minutes. 



PARASITISM. 



Considering the large numbers of individuals observed during 

 these investigations the total amount of parasitism was very low, 

 particularly among first-brood pupa? taken for the following emer- 

 gence records. 



That some parasitism of first-brood pupa? occurred is shown in 

 Table XXXVII. 



Table XXXVII. — Percentage of*> parasitism of field collected first-brood grape-berry 

 moth pupse from Venice, Ohio, 1917. 



Date of collection. 



July 26. 

 July 28. 

 July 30. 

 Aug. 1.. 

 Aug. 4. . 

 Aug. 6. . 

 Aug. 8.. 

 Aug. 10. 

 Aug. 20. 

 Do. 



Total. . . . 

 Average . 



Number 



Number 



of co- 



of para- 



coons col- 



sites 



lected. 



emerged. 



18 







34 



8 



32 



1 



41 



11 



64 



2 



47 



8 



51 



12 



35 



12 



8 







31 



4 



361 



58 



Percent- 

 age of 

 para- 

 sitism. 





 20.58 



3.12 

 26.82 



3.12 

 17.02 

 23.53 

 34.28 





 12.90 



16.06 



The parasitism of field-collected pupa? is seen to vary from to 26 

 per cent with an average of 16 per cent for pupa? collected between 

 July 26 and August 20. 



In a single instance, September 8, 1916, eggs of the berry moth 

 were found which were parasitized to an appreciable extent. A total 

 of 760 eggs were collected on 11 clusters, of which 236, or 31 per cent, 



