12 



spring the larvse in making their way toward the surface of the soil to 

 pupate will mostly work up in this ridge of earth, above the surface of 

 the roots, and there enter the pupal stage. The cultivation of the 

 vineyard in the spring should be so adjusted that this ridge of earth 

 may be thrown away from the vines when most of the insects are in 

 the pupal stage, as one of the regular cultivations. An implement 

 known as a "horse-hoe," generally used in vineyards, may be em- 

 ployed to great advantage in this work; but as it is not practicable to 

 remove the earth from immediately around the vine owing to danger 

 of injury, it is necessary to follow the horse-hoe at once and remove 

 the earth with a hand-hoe. The latter work is also done as a part of 

 the regular vineyard treatment to keep down weeds and grass, and is 

 timed so as to supplement the plowing with the horse-hoe for the insect. 

 Following the removal of the ridge of earth from along the vines, it is 

 well to keep the ground stirred at frequent intervals by means of a 

 cultivator to further insure the destruction of the pupae. 



GRAPE BERRY MOTH. 



The larva of the grape berry moth (PolycJirosis viteana Clem.) 

 infests 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 resembling 

 in appearance the injury due to the black-rot fungus, with which it is 

 frequently confused. Within the fruit the larvse feed on the pulp and 

 seeds, passing from one grape to another, and several of these discol- 

 ored and shriveling berries will often be found more or less webbed 

 together with numerous particles of larval excrement, and sticky 

 with exuding grape juice. Other insects attack the fruit of the grape, 

 such as the grape-seed insect (Isosoma vitis Saunders), whose larvse 

 feed on the seeds, causing the berries to shrivel late in the summer, 

 and the grape curculio (Craponius inaequalis Say), whose injury 

 closely resembles that of the grape berry moth and is considered on a 

 later page. But the principal cause of wormy grapes throuo;hout the 

 countr}^ is the larva of the species under consideration. Until recently 

 it was thought that our grape berry moth was introduced from 

 Europe many years ago. But Messrs. Slingerland and Kearfott have 

 shown," by careful study of this insect and related species, that the 

 insect infesting American vineyards is quite distinct from the Euro- 

 pean form (PolycJirosis hotrana Schiff). These gentlemen have also 

 shown that the American grape berry moth does not feed upon sumac, 

 as was formerly held, and consider it ver}?^ probable that the grape is 

 the sole food of this species. This important fact greatly simplifies 

 the question of its control, for if the species had other food plants 

 vineyards would be reinfested from outside sources despite thorough 

 treatments. 



Distribution and Destructiveness. 



The American grape berry moth occurs from Canada south to the 

 Gulf and westward to California. It is very generally distributed over 

 this area, and wherever the grape is grown it is more than likely to be 



oBul. 223, Cornell Univ. Agrl. Exp. Sta. (1904). 

 284 



