AN ENCYCLOPEDIA OF HORTICULTURE. 



93 



GRAPE OB VINE LOUSE (Phylloxera vastatrix). 

 This insect belongs to the Aphides, or Green Flies, a 

 group that contains many species very destructive to 

 field and garden crops, but none which approaches 

 this in the injuries done by it. The insect lives on the 

 European Vine (Vitis viniferd), forming galls on both 

 roots and leaves ; and, when it has once effected a settle- 

 ment, the plant, if left to itself, soon perishes under the 

 attacks. The injuries to the leaves are of compara- 

 tively slight moment ; the danger proceeds from the 

 effects produced on the young roots. The insects fre- 

 quently affix themselves near the tips of newly-formed 

 roots, and push their probosces through the bark, it may 

 be even to the cambium. There results from this a 

 thickening of the bark, due to the development of new 

 cells hence the formation of galls, some of which 

 reach the size of a pea ; and, after a time, the central 

 part of the root also becomes modified. In autumn, 

 the healthy young roots begin to undergo enlargement, 

 to form the older ones of the next year ; but, in those 

 affected, the galls die, and the roots also perish. The 

 plants are thus deprived of due nourishment, and are 

 starved ; while, at the same time, they are weakened by 

 the abstraction of food by the insects on the older roots 

 and leaves. Phylloxera vastatrix passes the winter on 



FIG. 147. GRAPE OR VINE LOUSE. 



the roots. In spring, the plants push out young 

 branches and leaves, but these soon become yellow, and 

 wither; and the fruits, if they ripen, often remain un- 

 coloured and sour. The next year, the leaves are still 

 more deformed; and fruits are not formed, or do not 

 ripen. The insects leave the Vines before the latter are 

 quite dead, and crawl about in search of new plants. 

 Hence, any diseased plant is a dangerous centre of infec- 

 tion in a vinery. The insects vary in appearance. Eggs 

 laid, in the autumn, between the crevices of the bark on 

 the roots, produce, in spring, larvae, which pass, with 

 little change, except mere increase in size, into the 

 mature females. These larvae usually form galls on 

 the leaves, but, at times, the roots alone are attacked. 

 The leaf-galls form small reddish warts on the one 

 surface of the leaf, with small depressions on the other 

 surface. In this depression is the entrance to the gall 

 a slit, closed with hairs. From the leaf-galls emerge 

 wingless insects, which continue for a time to form new 

 galls, and at last pass down to the roots. 



In Fig. 147, A shows sketch of a Vine root attacked by 

 phylloxera; B, portion of leaf of Vine, showing the galls 

 formed on the leaf by the Phylloxera, as seen both on 



Grape or Vine Louse continued. 



upper and under side ; and c, subterranean form of female, 

 magnified. The eggs are about s^in. long. The mature 

 female may reach *nin. in length, and varies in colour from 

 pale yellow to dull brown. The males become winged 

 when mature ; the body is about isin. or ^oin. long ; the 

 wings are nearly twice as long as the body. The colour 

 is golden-yellow, or approaches dull orange, except a dark 

 band across the thorax. The eyes are red in both sexes. 



History. The disease of Vines caused by Phylloxera 

 was first noticed in 1863, in Southern France, but did 

 not seem very dangerous till 1865. Planchon, in 1868, 

 discovered that it was caused by the insect, which, how- 

 ever, had been previously known to zoologists. In 1856, 

 Dr. Asa Fitch observed it in America, and named it 

 Pemphigus vitifolice. In 1863, it was discovered in 

 vineries near London, and was named by Professor West- 

 wood Peritymbia vitisana. In France, it spread very 

 rapidly, even till it reached the most northern vineyards. 

 In the department of Vaucluse, the yield of wine had, 

 in 1876, been reduced to about one-tenth of the former 

 amount. The disease still spreads, and has appeared in 

 most countries of Western and Central Europe. 



The effect of the legislation which the dread of the 

 Phylloxera has brought about, seriously interferes with 

 the nurserymen who export plants. In some countries 

 Germany, for example no plants are allowed to be im- 

 ported. An exception in this case, we believe, is made 

 in favour of " bulbs ; " but plants equally unlikely to be 

 in any way the means of furthering the spread of the 

 Phylloxera, are rigidly refused admission. In order to 

 send plants to any of the countries in which the regula- 

 tions of the Phylloxera Convention are enforced, it is 

 necessary to sign a declaration that the package contains 

 no Vines or roots of Vines, that no Vines are grown near 

 the place whence the plants were taken, and that no 

 Phylloxera exists, or has existed, in the immediate 

 neighbourhood. This declaration must be stamped and 

 countersigned by a magistrate, and afterwards be pre- 

 sented to the Consul or Vice-Consul of the country to 

 which it is proposed to send the package, for his vise". 

 The fee for the latter varies almost for every country. 

 The declaration is then handed to the agent or railway 

 company who undertake to forward the plants : without it, 

 the goods are not allowed to be sent to their destination. 



Remedies. These fall almost entirely under the head 

 of " Prevention of the Spread of Disease," which has been 

 attempted in various countries by strict prohibition of 

 the export of Vines from infected districts, and of the 

 import of Vines into places where disease has not yet 

 appeared (the German law of llth Feb., 1873, is espe- 

 cially strict in this matter). It has also been attempted 

 by the destruction of the Vines wherever disease has 

 appeared. The German law of 6th March, 1875, enforces 

 the thorough uprooting of infected plants, burning every 

 part, and a disinfection of the soil, for which many sub- 

 stances have been used the most reliable, however, is 

 carbon disulphide, which destroys the insects on the 

 roots, but does not injure the plants, especially if applied 

 in winter. A mixture of carbon disulphide and coal-tar 

 has also been advised; and a good mode of using it is 

 to scatter on the soil pieces of wood saturated in the 

 mixture, and washed with water-glass (silicate of pot- 

 ash), so as to allow the gases to pass off gradually as 

 the latter dissolves. Another method is, where easily 

 practicable, to lay the soil under water for six or seven 

 weeks. The American Grape Vines, especially V. cordi- 

 folia and V. cestivalis, resist the attacks of Phylloxera 

 far better than do the European species ; and, of late 

 years, they have been largely introduced into European 

 vineyards, for the purpose of supplying stocks on which 

 to graft the better flavoured, but more delicate, Old 

 World varieties. (" Enquete de 1' Academic des Sciences 

 sur le Phylloxera." Paris, 1879. 2 vols., with many plates.) 



