232 INSECTS INJURIOUS TO THE GRAPE. 



shall discover an efficient remedy for this insect pest. At the 

 same time it has made alarming progress in Portugal, also 

 in Switzerland and in some parts of Germany, and among 

 vines under glass in England. It is a native of America, 

 whence it has doubtless been carried to France ; it is common 

 throughout the greater portion of the United States and in one 

 of its forms in Canada ; but our native grape-vines seem to 

 endure the attacks of the insect much better than do those of 

 Europe. Recently it has appeared on the Pacific slope, in the 

 fertile vineyards of California, where the European varieties 

 are largely cultivated, and hence its introduction there will 

 probably prove disastrous to grape-culture. 



This insect is found in two different forms : in one instance 

 on the leaf, where it produces greenish-red or yellow galls of 

 various shapes and sizes, and is known as the type Galldecola, 

 or gall-inhabiting; in the other and more destructive form, on 

 the root, known as the type Radidcola, or root-inhabiting, 

 causing at first swellings on the young rootlets, followed by 

 decay, which gradually extends to the larger roots as the 

 insects congregate upon them. These two forms will for 

 convenience be treated together, a slight departure from the 

 general plan of this work. 



The first reference made to the gall-producing form was by 

 Dr. Fitch in 1854, in the " Transactions of the New York 

 State Agricultural Society," where he described it under the 

 name of Pemphigus vitifolise. Early in June there appear 

 upon the vine leaves small globular or cup-shaped galls of 

 varying sizes. A section of one of these is shown at c?, Fig. 

 241 ; they are of a greenish-red or yellow color, with their outer 

 surface somewhat uneven and woolly. Fig. 240 represents a 

 leaf badly infested with these galls. On opening one of the 

 freshly-formed galls, it will be found to contain from one to 

 four orange-colored lice, many very minute, shining, oval, 

 whitish eggs, and usually a considerable number of young 

 lice, not much larger than the eggs, and of the same color. 

 Soon the gall becomes over- populated, and the surplus lice 



