i74 THE CANADIAN IIOIiTICULTOj^RIST. 



insect life. Having deposited her eggs, the mother dies and shrivels, 

 but I'rom each of these eggs there hatches out a fertile female ; these 

 in their turn creep out of the gall and seek the young and tender 

 leaves upon which they fasten themselves, produce more galls, lay more 

 eggs, which again produce fertile females-. This process goes on 'for 

 five or six generations, so that the number towards the end of the 

 summer becomes immense-. Sometimes these insects are so crowded 

 "that they cover not only the leaves but also the tendrils, leaf stalks 

 ■and tender shoots, upon whicli their punctures form knots, as shewn 

 -at letter e, fig. 12. Suppose there should be one of these insects "on a 

 vine at the commencement of summer, and that she laid only two 

 hundred eggs, the lowest average number given by observers, and that 

 "each of these two liundred laid two hundred more, and that this is 

 •continued for five generations, we have 320,000,000,000 as the progeny 

 •of a single mother by the end of summer. Fortunately this prolific 

 •creature has its natural enemies, which serve to materially reduce the 

 number, so that at the end of summer they are not as numerous as 

 their wonderful fecundity would make them. 



In tlie autumn, wh-en the vines cease to make new growth, and 

 •consequently the lice can find no tended' leaves on which to feed, they 

 leave the foliage and descend to the ground and attach themselves to 

 the roots, from whence they seem to come again on the return of 

 summer, to puncture the young leaves and repeat the gall making 

 proceedings of their mothers. From the fact that no male louse has 

 ■ever been found among these gall makers, entomologists have con- 

 ■cluded that they ^re iMt the vagamic and apterous female form of the 

 a-oot-feeding type, w^hicli means that these never have wings, and never 

 marry, being but the transient summer state of the root4nfesting louse; 

 which at every third or fourth generation produces males, and as in 

 that generation both males and females have wingS) they can easily 

 spread through a vineyard^ and from one vine;^ard to another. 



These leaf gall lice do very little injury in comparison with that 

 •wrought by the root-inhabiting type, and by a little watchfulness in 

 the early part of summer in picking off and destroying all leaves 

 shewing any galls, the writer has found no difficulty in keeping them 

 in check. 



Fruit growers, and especially cultivators of the vine, are under 

 ^■reat obligations to Prof. C. V. Riley for the study bestowed by hire 



