40 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



No. 45. grape-vine-leaf gall-louse. The insect forms galls on the un- 

 der side of the grape-vine leaves, and although they appear 

 to do comparatively little injury to the vine, they are ex- 

 tremely interesting to vine-growers, as having been said by 

 Professor Kiley and other entomologists to be another form 

 of the Phylloxera vasiatrix or the grape-vine-root gall-louse, 

 so destructive to the vineyards in France and elsewhere. 

 The female of the grape-vine-leaf gall-louse, after fixing her- 

 self on the upper side of a leaf, by constant suction and the irrita- 

 tion produced by continued puncture, causes a gall to swell irreg- 

 ularly on the under side, while the upper side gradually becomes downy 

 or hairy and partially closes, forming a little bag on the under side, 

 with a small opening on the upper surface, surrounded with hair-like 

 filaments. In this bag or gall the female lives, and deposits from fifty to 

 some hundreds of small yellow eggs. Dr. Shimer states that there are 

 500 eggs in one gall, which is doubted by Walsh, who estimates that 

 probably two hundred eggs will be the average number laid by one 

 female. The figure is magnified. 



Phylloxera vastatrix, or the grape-vine- root gall-louse, is by many ento- 

 No. 46. mologists supposed to be another form of the Pemphigu9 viti- 

 V ^ folia; above mentioned, but that, instead of living above ground 

 /ik^s ^^^ forming hollow bag-like galls on the leaves, it lives under- 

 ground on the roots, upon which it forms knotty swellings or 

 galls. Mr. Eiley, who has paid more attention to the natural 

 fj history and habits of this insect than any other entomologist 

 in this country, is of the above opinion. The young of the 

 root-inhabiting type {Phylloxera vastatrix) are absolutely undistin- 

 guishable from those hatched in the leaf-galls, {Pemphigus vitifoUx 

 of Fitch,) and the gravid apterous female differs in no respect 

 from the mother gall-louse. There is, however, a diflerenfc egg-pro- 

 ducing form, which, as it molts, becomes tubercled and more elon- 

 gate or pear-shaped. Some of these tubercled individuals remain 

 v;ithout v/ings, while others acquire wings. The insect is found on the 

 roots in all stages during the summer months, and in spring, when the 

 sap begins to circulate, eggs are deposited, and the young lice by sucking 

 produce the swellings produced on the roots. The winged lice begin to 

 emerge from the earth as early as July, and the female has only two or 

 three large eggs in her body ; and Professor Riley says that her whole 

 duty in life is to fly oli" and consign her two or three eggs to some grape- 

 vine or bud, and that the lice hatching from these eggs constitute the 

 first gall-producing mothers that form the excrescences on the leaves and 

 have a great number of eggs. These insects attack both leaves and 

 roots in the summer at the same time, but the roots appear to bo less 

 infested when the leaf-galls are abundant, and may be extremely 

 abundant on the roots when no galls whatever are seen on the leaf. In 

 order to prove the identity of the leaf-gall louse with the root-gall louse 

 of the grape-vine, it is stated that very young gaU-lice hatched from the 

 leaf-galls have been transferred to the roots, and by successfully feeding 

 them on roots the smooth-skinned gall-inhabiting type gave birth to the 

 tubercled root-inhabiting type. In our own experience, however, as an 

 experiment, several small vines were placed in a kind of Wardian case, 

 having the roots covered with the swellings and the root-inhabiting 

 type, {Phylloxera vastatrix.) Other healthy vines were also potted and 

 placed in juxtaposition to the infested specimens, in order to see if the 

 gall-inhabiting type would make their appearance in the spring on the 

 leaves. The vines wintered safely, and in the spring and summer pro- 

 duced large healthy leaves on which no gaUa whatever made their ap- 



