24:8 



IIn^JUEIOUS mSECTS 



THE GRAPE PHYLLOXERA. 



{Phylloxera vastatrix, Planchon.) 



This minute insect, which has caused such devasta- 

 tions in the vineyards of Europe, is a native of this 

 country, where its destructive work Avas known long be- 

 fore the cause of it was discovered. The life history 

 of the Phylloxera has been worked out by Prof. 

 Riley in his Missouri Re23orts, especially in the Sixth, 

 from which the following account is condensed. 



The insect presents itself under several different forms, 

 all of which belong to two types. One of these is the 

 Leaf -gall type [galUcola, R.), and the other is found 

 upon the roots of the vine {radicicola, R.). 



FiKST, AS TO THE Leaf-gall Type (GalUcola.) — 

 The gall or excrescence produced by this is a fleshy 

 swelling of the under side of the 

 leaf, more or less wrinkled and 

 hairy, with a corresponding depres- 

 sion of the upper side, the margin 

 of the cup being fuzzy, and 

 ^ . Z]^' o 1. drawn too-ether so as to form a 



a and 6. Elongated Galls : c 



and d^up^er^and imd^^^^^ fi'ii^ged moufch. It is usually cup- 

 shapecl, but some times greatly 

 elongated or purse-shaped (figure 151, a, d). 



Soon after the first vine-leaves that put out in the 

 spring have fully expauded, a few scattering galls may be 

 found, mostly on the lower leaves, nearest the ground. 

 These vernal galls are usually large (of the size of an 

 ordinary pea,) and the normal green is often blushed 

 with rose where exposed to the light of the sun. On 

 carefully opening one of them (fig. 152, cl), we shall find 

 the mother-louse diligently at work surrounding herself 

 with pale-yellow eggs of an elongate oval form, scarcely 

 , 01-inch long, and not quite half as thick (fig. 152, 



