GRAPE-BEERY MOTH IN NORTHERN OHIO. 



11 



PLACE OF OVIPOSITION ON THE VINE. 



It was found that a vine of the Clinton variety set in a row of 

 Concords was heavily oviposited upon before the Concord berries 

 were formed. For use in the spacing of spray nozzles for the set- 

 nozzle method of spraying, the place of oviposition on the vine 

 seemed important. The place of oviposition on this one vine by 

 the spring brood of moths was recorded and the data are presented 

 in Table XIV. The vine was trained according to the fan system 

 of grape training which is generally used for all varieties in the north- 

 ern Ohio sections. In the fan system the vine growth which is 

 trained to an upright trellis is annually renewed to within a short 

 distance of the ground. The vines are cut back usually to from 2 to 

 4 canes and as many spurs each year; the canes are spread out and 

 tied to the trellis obliquely, giving the shape of a fan. 



Table XIV. — Place of oviposition on vine by spring moths of the grape-berry moth 

 under natural conditions in vineyard, Venice, Ohio, 1917. 





Dis- 

 tances. 



Num- 

 ber of 

 clusters. 



Num- 

 ber 

 grapes 

 bearing 

 eggs. 



Num- 

 ber 



eggs. 



Num- 

 ber 

 eggs 

 per 



cluster. 



Percentage of— 



Place on vine. 



Depo- 

 sition 

 in this 

 space. 



Clusters 

 in this 

 space. 





Inches. 



21 



21-33 



33-49 



15 



23 

 7 



S2 

 260 

 124 



107 

 333 

 190 



7 

 15 

 29 



17 

 53 

 30 



33.3 





51.1 





15. 5 







Total 



45 



466 



630 



14.0 



100 



100.0 























The figures in Table XIV agree with the usual observation that 

 the clusters near the ground are less heavily infested than those 

 higher up on the vines. Thirty per cent of the deposition occurred 

 between the middle wire and top wire, whereas but 15 per cent of 

 the clusters were in that space. These figures likewise agree with 

 field observations in that the heavy infestation is generally where 

 the clusters are well covered with foliage, a condition which prevails 

 near the top of the trellis. 



In Table XV are presented records of the length of the incubation 

 period of eggs of the first brood. The average number of days 

 required for incubation was 4.39, the maximum 8 days, and the 

 minimum 3 days. These figures include both insectary material and 

 eggs collected in the vineyard when the date of deposition was known. 

 In obtaining the eggs from the vineyards all eggs were removed from 

 the vines each day. 



