46 
Perhaps the most satisfactory feature of the case is that, although 
the insect must have been introduced nearly four years ago, it does 
not appear to have spread. Although I examined the roots of numerous 
vines in Remuera and other places, no instance of its occurrence came 
under my notice, nor could I hear of any one who had seen it. Mr. 
Allen informed me that he had some rooted cuttings taken from the 
waste prunings of the affected vines last year, and invited me to 
examine them in his garden, which I did, but was unable to observe 
any trace. of the insect. Sowe of these cuttings forwarded to 
Wellington, and kept in soil in a ‘warm room, have remained perfectly 
clean up to this date. 
Now, it is extremely difficult to imagine that typical Phylloxera 
vastatriz could have remained for between three and four years with- 
out having spread to vines in adjacent gardens and vineries. Such an 
occurrence could only be explained by the non-development of winged 
forms during that period—a phenomenon at variance with all that is 
known of its life-history. 
Life-history of Phylloxera vastatriz.—This remarkable aphidian 
insect exhibits two series of forms—one infesting the roots of vines, 
the other the leaves and stem. They have been distinguished by 
Professor Riley as Radicicola and Gallicola respectively. Both series 
exhibit a wide diversity of form, and the larve vary in appearance 
with each successive moult. More than twenty different forms were 
drawn and described by M. Lichtenstein in 1876. In Europe the 
subterranean form effects the greater amount of injury; in America 
the aerial forms are most dreaded. The winged aerial female is 
developed from atrue egg deposited the previous autumn, and is about 
0070 of an inch in length, flask-shaped, and contains numerous 
pseudova; the suctorial beak is about one-fourth the length of the 
body. She becomes the mother of the colony, and punctures the leaf 
in such a way as to cause an increased flow of sap to the wounded 
parts, resulting in an unhealthy growth, which forms a gall completely 
surrounding the insect; in this gall she deposits many hundreds of 
ege-like bodies during the summer months. After the larve have 
developed they descend to the roots in such vast numbers as to give 
the fibres the appearance of having been dusted with flour. The bark 
of the root decays and falls away, while small knots or galls are formed 
on the fibres. The affected vines at this stage present an unhealthy, 
stunted appearance. The wingless subterranean female is only 0:026 
of an inch in length, and her body contains but few eggs. She produces 
five or six generations, so that larve of various sizes and different 
forms are found on the same root. Shortly after midsummer many of 
her progeny develop wings and ascend to the surface, when they 
migrate to other districts, where they produce true males and females, 
the latter being more numerous than theformer. In thiscondition they 
are about 0°120 of an inch in length; each contains a single egg, about 
0°015 of an inch long, which will give rise to the true male or female, 
the egg from which the last is developed being larger than that which 
