Insects. 



GRAPE MANUAL. 



Phylloxera. 65 



Type Galt.icola: 



wliich differ from their mother 

 ill their brighter yellow color, 

 more perfect legs, etc. Issu- 

 ing from the mouth of the 

 gall, these youug Hce scatter 

 over the vine, most of them 

 finding their way to the tender 

 terminal leaves, and com- 

 mence pumping up and ap- 

 propriating the sap, formiug 

 eg},'; d, soctioii of galls and depositing eggs as 



""till f^nla r"'Ofl ' ^ • • « i " oo 



swellins of tendril! ^^^^^' immediate parent had 

 nat. size. ' done before. Tliis process 



continues during the summer, 

 until the fifth or sixth generation. Eveiy egg 

 brings forth a fertile female, which soon be- 

 comes wonderfully prolific. 



By the end of Sep- 

 tember the galls are 

 mostly deserted, and 

 those which are left 

 appear as if infected 

 with mildew, and 

 eventually turn 

 brown and decay. 

 The young lice at- 

 tach themselves to 

 the roots, and thus 



hibernate It is an newly Hatched Gall-Louse: 

 important fact that «, ventral; 6, dorsal view. 

 the gall-inhabiting 



insect occurs only as an agamic and apterous 

 female form. It is but a transient summer state, 

 not at all essential to the perpetuation of the 

 species, and does, compared with the other, or 

 root-inhabiting type, but trifling damage. It 



flourishes mostly on 

 the Riparia, more 

 especially on the 

 Clinton and Taylor; 

 its galls have also 

 been noticed on 

 many other varie- 

 ties. In some sea- 



^£- y '"^<r^^^^^::i^ sons it is even diffi- 



^^=?r" ^"^fyi^ ,3i,lt to f^^^ a few 



galls on the very 

 vines on which they 

 were very abundant 

 the year before. 

 The root-inhabiting type of the Grape Phyl- 

 loxera hibernates mostly as a young larva, at- 

 tached to the roots, and so deepened in color 

 generally as to be of a dull brassy brown, and 

 therefore perceived with difficulty, as the roots 

 are often of the same color. With the renewal of 

 vine-growth in the spring, this larva moults, 

 rapidly increases in size, and soon commences 

 laying eggs. These eggs, in due time, give birth 

 to young, which soon become virginal, egg-laying 

 mothers like the first, and, like them, always re- 

 main wingless. F'ive or six generations of these 

 egg-bearing mothers follow each other, when, 

 about the middle of July, in the latitude of St. 

 Louis, some of the individuals begin to acquire 

 wings, and continue to issue from the ground until 

 vine-growth ceases in the fall. Having issued 

 from the ground while in the pupa state, they rise 

 in the air and spread to new vineyards, where 

 they lay from three to five eggs, and then perish. 

 In the course of a fortnight these eggs, which are 

 of two sizes and are deposited in the crevices on 

 the surface of the ground, near the base of the 

 vine, and upon the leaves, especially on the under 



'.\ 



l"i<r. 83. Mother Gall-Louse: 

 ventral and dorsal views. 



Male Phylloxeka: 

 ventral view. 



side', produce the sexual in- 

 dividuals, which are born 

 for no other purpose than 

 the reproduction of their 

 kind, and are without means 

 of flight or of taking food. 

 They are, liowever, quite 

 active and couple readily. 

 The males coming from the 

 smaller and the females from 

 the larger eggs. 



The female lays a single 

 ^gg, which has been called 

 the "winter egg," from the 

 fact that it generally passes 

 the winter unhatched. It is 

 generally hidden in the crev- 

 ices and under the loose bark of the older wood, 

 but may also be laid in other situations, and 

 even on old leaves on the ground, It is distin- 

 guished from all the other eggs produced by 

 other forms of the insect in that it has an olive- 

 green hue and a short pedicel at one end. 

 There hatches from it the " stem-mother," which 

 either goes directly on to the roots to found a 

 root-feeding colony, or more often founds a 

 gall-inhabiting colony on the leaf, the gall- 

 inhabiting form always issuing from such winter 

 eggs. 



Every jjiece of root having rootlets taken from 

 an infected vine during August or September will 

 present a goodly proportion of pupte, and a glass 

 jar filled with such roots and tightly closed will 

 daily furnish, for some time, a dozen or more 

 winged females, which gather on the side of the 

 jar toward the light. We may gather some idea 

 from this fact, of the immense number that dis- 

 perse through the air to new fields from a single 

 acre of infected vines, in the course of the late 



Pig. 85. 



Type Rauicola: showing the tubercles by 



which it is distinguished from GalUcola. 



summer and fall months. We have, therefore, the 

 spectacle of an underground insect possessing the 

 power of condnued existence even when confined 

 to its subterranean retreats. It spreads in the 

 wingless state from vine to vine and from vine- 

 yard to vineyard, when these are adjacent, either 

 through pa.ssages through the ground itself, or 

 over the surface ; at the same time it is able, in 

 the winged condition, to migrate to much more 

 distant points. 



If to the above account we add that occasionally 

 individuals, under certain conditions, abandon 

 their normal underground habit, and form galls 

 upon the leaves of certain varieties of grape- 

 vines, and that under certain conditions the root- 

 inhabiting form may propagate for several years 

 without producing the aerial or winged form, we 

 have in a general way the natural history of the 

 species. 



