124 PROCEEDINGS OF THE CALIFORNIA 



most readily be destroyed, arid believing that this form -was one which was 

 necessary for the continuation of the species, its destruction would necessarily 

 be followed by the disappearance of all the other forms. 



The bisulphide of carbon seemed to present the only agent likely to be effi- 

 cacious against the insect. Owing to the extreme volatility of this substance, 

 its vapor, when it is introduced at some distance beneath the surface, would 

 permeate the earth in all directions over a considerable area, and thus would 

 have a chance of reaching even the distant rootlets of the vine. Although it 

 had been reported in France that the substance was not destructive to the in- 

 sect, yet I believed that the soft, apparently nude form, which I had just dis- 

 covered, would not resist it. In order to introduce the substance beneath the 

 ground, an iron tube was taken with a sharp steel point at one end, the sides 

 beiDg pierced with a few small holes near the bottom, and a piston was made 

 which could be forced down the tube. The tube was driven into the earth for 

 a distance of one or two feet, near the root of the vine; some bisulphide of 

 carbon was poured into the tube, which was then filled with water, and the 

 contents of the tube forced out into the ground with the piston. The tube 

 was then drawn out and the hole filled up. The quantity used on each vine 

 was about an ounce and a half of the bisulphide. This was introduced into 

 the ground through two or three holes. The substance was applied in the end 

 of April and early part of May, only one application being made, and in ev- 

 ery instance to plants that were evidently suffering from the disease. The 

 result has been, on the vines so treated the insect has almost entirely disap- 

 peared, while on vines that were in the same condition last year as those to 

 which the bisulphide had been applied, but which were not treated, the roots 

 swarm with the insect, so that none of them are likely to survive this season, 

 at least of those that were most affected. In the early part of the season no 

 great difference was noticed between the foliage of the vines that had been 

 treated and the others, but within the last six weeks the vines on which the 

 insect had been destroyed present a decidedly healthier appearance. A more 

 marked difference is observable in the roots, specimens of which I submit for 

 inspection. It will be seen that while the roots of the vines to which the bi- 

 sulphide has been applied present a comparatively smooth and healthy ap- 

 pearance, the roots of the untreated vines are rough and covered with dead 

 and decaying bark. In both sets of roots the lower portion is generally dead, 

 the result of the ravages of the insect during the last season; but while in the 

 plants which are still infested with the insect this process is still going on and 

 will continue until the vine is destroyed, the other roots are throwing out 

 quite a number of healthy rootlets and are covered with a new and smooth 

 bark, so that they will be prepared in the ensuing year to throw out a new 

 crop of rootlets. 



As regards the practicability of the treatment this presents no obstacle, as 

 the bisulphide of carbon can be obtained now in a comparatively pure state at 

 fifty cents per pound; and I am confident it can be produced in a form quite 

 suitable for use iu the vineyard at a third of the price, so that the cost of the 

 material for each vine would not exceed two or three cents. The process of 

 applying it is simple, and can be carried out by any ordinary laborer. The 



