DISEASES OF THE VINE. ] 599 



developing galls, become pro-nymphs and then nymphs, 

 and after four moults develop into the winged insect. 

 These nymphs are more numerous on the nodosities of 

 the roots, and the winged insects which result from them 

 and fly away in the course of afternoon, are always 

 sexuparous, that is their offspring have sexual characters. 



These winged sexuparous insects are reddish or 

 orange- red with the exception of the second thoracic 

 segment which is black, the length of the body being i 

 to i^ m.m. The antennae are about one third the 

 length of the body ai.d terminate in a fine point. The 

 eyes are reel, with three eyelets. The beak is short, 

 and the feet are long. The abdomen his eight distinct 

 segments, narrowed posteriorly, but obtuse. The wings 

 are transparent and iridescent, the anterior pair being 

 much larger and longer, and both pairs are disposed 

 horizontally on the body when the insect is resting. 

 The sexuparous winged insect deposits its eggs parthe- 

 nogenetically on the stem and branches of the vine, 

 chierly in the fissures of the bark, but occasionally 

 also on the foliage, each winged insect depositing 

 only female eggs or only male eggs, usually only one 

 in number but occasionally as much as five or six. 

 These eggs are elliptical or elongated, of a shining 

 yellowish white, with a slightly netted surface, the eggs 

 which give birth to female individuals being f- of a 

 millimeter in length, and about J of a millemeter in 

 thickness, while the eggs which give birth to male indi- 

 viduals -are smaller. In July- August these eggs are 

 hatched, and the young after about four days, copulate 

 and the fertilized female proceeds to hide as deeply as 

 possible in the fissures of the bark or under the bark, 

 where in about 24 hours it lays the winter egg. 



On the European vine the life-cycle of the Phylloxera 

 is modified. It is generally held that the sexuparous or 

 winged insect is produced all the same, but that it seeks 



