DISEASES OF THE VINE. ] 597 



vine grower has now to deal with this dreaded parasite 

 and to take his precautions accordingly. 



The Phylloxera of the vine is not known to attack 

 other plants besides the various .species of the genus 

 Vitis, and lives on the roots and foliage of the American 

 vines without causing any serious trouble. Its leaf-galls 

 are rarely lound on the foliage of the European vine, but 

 the roots ol this species and its varieties are so suscepti- 

 ble to this pest that the plant sooner or later succumbs 

 to the attack. 



The life-cycle of the insect on its natural host plants, 

 the American vines, is the following. The female insect 

 which has been fertilized late in -summer or in autumn, 

 deposits a slightly cylindrical egg, uith a hooked prolon- 

 gation -at one end, and a dark red, small micropile at 

 the other end. This egg is deposited deep in the fissures 

 of the bark of the stem or branches, and is at first bright 

 yellow, but in 24 hours becomes definitely of a bright 

 olive green, with its surface wrinkled and dotted. This 

 egg hatches in spring and the young larva (foundress 

 larva or mother larva) proceeds to the upper surface of a 

 leaf to which it fixes itself by its long beak, and causes 

 the formation of a small purse-shaped or wart-shaped 

 gall, usually protruding on the under surface of the leaf 

 with its opening or o.rifice on the upper surface surround- 

 ed by many rigid hairs, but sometimes the opening is on 

 the under surface and the gall protrudes on the upper 

 surface. These galls are sometimes found on the ten- 

 drils or on the petiole of the leaf, and there may be quite 

 a number of these galls on the same leaf. These galls 

 are rarely found on the European vine, but are common 

 on the American vines and also on their hybrids, and the 

 winged insect which deposits the winter egg has the 

 instinct to seek out .the American vine to deposit the egg 

 on its stem, in preference to the European vines which 

 may be in close proximity, but in any case the injury 



