598 [ DISEASES OF THE VINI. 



caused by the presence of these galls on the foliage is 

 quite unimportant. The larva within the leaf gall, after 

 four moults becomes a gall-larva (gallicoia), and is a 

 wingless insect about. \ \ m.m. long and i m.m. thick, 

 and is a yellowish or greenish colour, with short legs and 

 no tubercles on its back, but with red eyes and 3 -jointed 

 feelers, of which the first and second joints are short and 

 thick, but the third is long and pointed. This wingless 

 insect proceeds to lay parthenogeneticaliy about 600 

 eggs, which are roundish or slightly elliptical, pale 

 yellow and pellucid. These eggs are about \ m.m. in 

 length, and each becomes covered by a netting showing 

 hexagonal meshes. From these eggs are hatched the 

 neogallicolous larvae, which coming out of the orifice of 

 the mother gall, produce other galls on the ioliage. and 

 in this manner there may be three to five generations. 

 Among the neogallicolous larvae of the third generation 

 there may be some which abandon the upper parts of the 

 vine and descend to the roots where they become 

 galticolous-radicicolous, and many or most of the larvae 

 of the fourth and fifth generations adopt also the 

 parasitic life on the roots, where they produce the 

 characteristic uncinate galls on the rootlets or develop 

 small colonies on the larger roots. 



The larva met with on the roots is wingless, of an 

 oval form, and often pyriform, terminated behind in a 

 prolonged and pointed abdomen. The colour is yellowish 

 or reddish, but in winter is brown. The last joint of the 

 antennae is thin, but much longer than the corresj onding 

 joint of the antennae in the larva which inhabits the galls 

 on the rootlets. Theie are seventy tubercles on^ the 

 back, each terminated by a hair, and the feet are s"hort 

 and stumpy. 



On the roots, also, the Phylloxera multiplies par- 

 thenogeneticaliy, but from the third generation, which 

 takes place in June and onwards, some larvae instead of 



