THE GKAPE-BERKY MOTH. 



39 



Table XIV. — Length of the feeding period of second-brood larvse of the grape-berry moth 

 in fruit on the vines under large outdoor rearing cages, North East, Pa., 1909. 



Number 

 of larvae. 



Larvse 

 hatched. 



Larvse 

 left fruit. 



Number 

 of days. 



Number 

 of larva?. 



Larvse 

 hatched. 



Larva? 

 left fruit. 



Number 

 of days. 



6 

 1 

 3 



9 

 1 



8 

 7 

 7 

 10 

 8 



Aug. 25 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



Sept. 25 

 Sept. 26 

 Sept. 27 

 Sept. 28 

 Sept. 29 

 Oct. 2 

 Oct. 3 

 Oct. 4 

 Oct. 5 

 Oct. 6 



31 

 32 

 33 

 34 

 35 

 38 

 39 

 40 

 41 

 42 



9 Aug. 25 

 1 ...do 



6 ...do 



7 ...do 



7 ...do 



1 ...do 



Oct. 7 

 Oct. 8 

 Oct. 9 

 Oct. 10 

 Oct. 11 

 Oct. 17 



43 

 44 

 45 

 46 

 47 

 53 

 40.3 

 53 

 31 



Maxi 

 Mini] 















The infested grape clusters were removed from the cage just 

 before the larvse were ready to leave the berries. These larvae 

 hatched from eggs deposited between August 20 and 25. It was 

 impossible to determine the exact date of hatching of all of the eggs, 

 but only a very small number hatched previous to August 25 and 

 this may account in a measure for the shorter average period of 

 feeding than is recorded for the larvae from the stock jars. In addi- 

 tion to this all but one of these larvae had left the fruit previous to 

 the occurrence of a decided drop in temperature between October 

 12 and 20 ; whereas only two of the larvae had emerged from the 

 fruit in the stock jars. Hence, since insect activities were slight 

 during this cold wave the period spent in the fruit by those larvae 

 which had not escaped previous to its occurrence was abnormally 

 prolonged. 



The minimum period spent in fruit by larvae in the rearing cage 

 was 31 days as against 40 days by those in stock jars; the average 

 40.3 days as against 52.6 days, and the maximum 53 days as against 

 63 days. 



Date second-brood larvse leave fruit. — A record was made of the period 

 during which the larvae leave the berries, with a view to ascertaining 

 whether many of them are likely to be removed from the vineyard 

 when the ripe grapes are being marketed. A large number of larvae 

 which infested grape clusters were collected from vineyards August 

 20-24. At this date few if any of the larvae of the second brood 

 had fully matured. Since the emergence of the two broods of moths 

 overlap it is quite likely that some of the larvae in this record belong 

 to the first brood. Daily examinations of the collected material 

 were made and the record of the larvae leaving the fruit is given in 

 Table XV. 



