STATE HORTICULTURAL SOCIE'JY. 



179 



damage is done. There was no end to the surmises as to the cause of the 

 disease in France, until Prof. J- K- Tlanchon announced that it was owing 

 to the puncture of this phylloxera. 



In 1869, M. J. Lichtenstein, of France, suggested that the European 

 phylloxera was the same as our gall insect. In 1870 I visited France, and 

 studied this insect in the field, and in 1871 I was able to give proof of the 

 identity of the two insects. In my third, fourth, and fifth reports, where 

 these facts are given at length and in detail, I have shown that the fail- 

 ure of the European vine, and the partial failure of many hybrids, are 

 owing to the injurious work of this insidious little louse. It had been at 

 its destructive work for years, and produced injuries to the vines, the 

 nature of which was not known until the appearance of my fourth report. 



This article attracted great attention, because in it I demonstrated 

 the above-named facts, and urged the use of stocks as a means of supply- 

 ing the place of the blighted vineyards of southern France. During this 

 time the disease was still raging in France. The plague had spread in 

 France, Italy, and Germany, and also in England, among the hot-house 

 grapes. 



Last fall, Prof. Planchon spent a month in this country, and all my 

 previous conclusions were verified by what he found here. First of all, 

 we have on the leaves of some of our varieties of vines, especially on those 

 belonging to the Riparia, a gall or excrescence on the under side of 

 the leaf, which sometimes covers the leaf, as is shown in the illustration. 

 (See Fig. i.) If we examine them, we shall find that there are a great 

 number of pale yellow eggs 

 in each, with a dark yellow 

 mother-louse. Sometimes you 

 will find not less than a thou- 

 sand of these eggs in a single 

 gall. Every one of these pro- 

 duces a louse. (See Fig. 2.) 

 Each one of these lice is a 

 female, and is capable of 

 forming new galls by punc- 

 turing the leaf with its pro- 

 boscis. The young louse 

 crawls and forms a new gall 

 without impregnation. It 

 increases until it becomes 

 like its mother in size, and 

 is soon surrounded by five or 

 six hundred or a thousand 

 eggs. Now, if from a single 

 mother-louse a thousand eggs 

 are obtained, in five genera- 

 tions the number of lice will 



foot up one thousand billions of individuals; and we can form some 

 conception of this immense number when we reflect that, small as the 



Fic. I. 



LEAK SHOWINt; GALLS. 



