VOL. II.] Phylloxera, 309 



point where an. imperfect knowledge of the biology of the msect 

 has injured the farmer and helped the pest. 



There was a time when it was considered sound policy to pull out 

 the infested roots and drag them through the vineyard to a spot 

 where, when a sufficient number had been accumulated, and when 

 they all appeared sufficiently dry .to take and hold fire, the torch 

 was applied to what was supposed to be the funeral pyre of the 

 Phylloxera. But this supposed funeral pyre was 'in fact the breed- 

 ing place of new colonies of the insect pest. The starving Phyl- 

 loxera had produced the winged generation before the pile of roots 

 was dry enough to take fire, and had been wafted away by currents 

 of air to infest the region with new colonies. Even the rootlets, 

 shaken ofT in carrying the infested vines to the pile, formed new 

 centers for the production of winged generations, and thus it can 

 easily be explained that this sanitary measure proved quite the re- 

 verse of what it was intended for. Experience has fully demon- 

 strated that the pulling out of the infested vines aggravated the 

 calamity. This danger may be avoided to a great extent by de- 

 stroying the vines on the spot, or making them unfit to serve as 



food for the pesf. 



It may be permitted here to suggest a method of fighting the 

 pest. I would advise the owners of vineyards in which the infested 

 spots are not yet confluent to surround them and cover them with 

 a layer of the substance called gas lime, which recommends itself 

 by its cheapness as well as by its efficacy. It is, so far as I know, 

 of no commercial value and can easily be obtained at gasworks, 

 perhaps for the mere expense of removal. At the same time it 

 does not, like petroleum and similar substances, entail permanent 

 steriUty on the localities where it is used; but on the contrary, being 

 washed into the soil by the rains will serve as a fertilizer. 



My experiments have convinced me, that a layer of an inch 

 thickness is more than sufficient to prevent the escape of the winged 

 generation. A thicker layer, of course, is necessary to destroy 

 speedily and effectually the vines of the healthy area. 



The method recommended here, will require perhaps an addi- 

 tional quantity of gas lime, or some modification of it, to destroy the 

 •gall-forming variety of the Phylloxera. This variation must be very 

 local in California or is generally rare, because during all my ex- 

 periments and investigations from the year 1869 to 1S80, I have not 



