66 INSECTS AFFECTING VEGETATION 



quent intervals by means of a cultivator to further insure the destruc- 

 tion of the pupae. 



Grape Berry Moth. The larva of the grape berry moth in- 

 fests the berry or fruit of the grape. The first generation attacks 

 and webs together the grape clusters even before the blossoms open 

 or soon after the grapes are set. Later-appearing larvae bore into 

 the green or ripening fruit and produce a purplish spot much re- 

 sembling in appearance the injury due to the black-rot fungus, 

 with which it is frequently confused. Within the fruit the Iarva3 

 feed on the pulp and seeds, passing from one grape to another, 

 and several of these discolored and shriveling berries will often be 

 found more or less webbed together with numerous particles of 

 larval excrement, and sticky with exuding grape juice. The 

 American grape berry moth occurs from Canada south to the Gulf 

 and westward to California. In some vineyards a loss of from 25 

 to 50 per cent of the crop is not infrequent, and in occasional in- 

 stances the destruction of the fruit is practically complete. 



The grape berry moth is small, the wings expanding not quite 

 one-half inch. The general color is purplish brown, the wings 

 with) markings. Moths appear in the spring from hibernating 

 pupae, beginning about the time the shoots of the grape are push- 

 ing out, and continuing to emerge for some weeks. The earlier- 

 appearing individuals deposit their eggs on the blossom clusters, 

 while those coming out after the blossoms are shed oviposit on the 

 clusters of young grapes. 



About 3 weeks are required for a larva to complete its growth 

 in summer, when it is about three-eighths of an inch in length, 

 slender, light greenish to purplish in color, the head slightly bi- 

 lobed, greenish above, and brownish in front, the thoracic feet 

 blackish. When ready to pupate the larvae go to the leaves, and a 

 small portion is cut loose, except along one side, and bent over and 

 fastened down with silk. Beneath this a thin, whitish, silken 

 cocoon is spun, and in 3 to 4 days the larva changes to a light 

 greenish brown pupa, from which the moth will emerge in some 

 12 to 14 days. Second-brood Iarva3 infest the grape during July 

 and August, the later-appearing individuals probably not devel- 

 oping to moths but hibernating in the pupal condition. Many of 

 the earlier-appearing insects of this brood appear to complete their 

 life cycle, and moths develop, giving rise to a third generation of 

 larvae. 



The use of arsenical poisons against the first brood of the grape 

 berry moth was recommended by Mr. Marlatt, of the Bureau of 

 Entomology, in 1895. Since this time the recommendation has 

 been amply justified in the experience of numerous vineyardists, 

 who, in connection with the fight against the grape root-worm, 

 found that their early sprayings for this pest were also controlling 

 the grape berry moth. Professor Slingerland reports an instance 

 in which three timely applications of arsenate of lead, at the rate 

 of 10 or 12 pounds to 100 gallons of water, gave almost absolute 

 protection during the rest of the season. 



