238 



INSECTS INJURIOUS TO THE QRAPE. 



ates are also recommended ; these are gradually decomposed 

 in the soil and give off sulphuretted hydrogen and bisulphide 

 of carbon. Carbolic acid mixed with water, in the propor- 

 tion of one part of the acid to fifty or one hundred parts of 

 water, has also been used with advantage, poured into two or 

 three holes made around the base of each vine with an iron 

 bar to the depth of a foot or more. Soot is also recommended 

 to be strewed around the vines. 



It is stated that the insect is less injurious to vines grown 

 on sandy soil, also to those grown on lands impregnated with 

 salt. 



Since large numbers of these insects, both winged and 

 wingless, are known to crawl over the surface of the ground 

 in August and September, it has been suggested to sprinkle 

 the ground about the vines at this period with quicklime, 

 ashes, sulphur, salt, or other substances destructive to insect 

 life. The application of fertilizers rich in potash and ammo- 

 nia, such as ashes mixed with stable-manure or sal ammo- 

 niac, has been found useful. A simple remedy for the gall- 

 inhabiting type is to pluck the leaves as soon as the galls 

 appear and destroy them. 



Several species of predaceous insects prey on this louse. 

 A black species of Thrips with w^iite-fringed wings (Thrips 

 phylloxerse Riley, see Fig. 244) deposits its eggs within the 



gall, which when hatched 



produce larvae of a blood- 



"//fH^^^^ red color, which play sad 



havoc amono: the lice. 



The larva of a Syrphus 

 fly, Pijnza radicum, which 

 feeds on the root-louse of 

 the apple (see Fig. 2), lias 

 also been found attacking 

 the Phylloxera. Another 

 useful friend is a small mite [Tyroglyphus phylloxerse P. & 

 R., see Fig. 245), which devours the lice; and associated with 



Fig. 244. 



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