THE GRAPE VINE. 



119 



inferior surface flattened, its dorsal surface convex, being sur- 

 rounded by a kind of fillet, which is very narrow when it touches 

 the thoracic part of its body, which (formed by five rather indis- 

 tinct rings) is hardly separated from its abdominal part of seven 

 rings. 



" Six rows of small blunt tubercles form a slight protuberance 

 on the thoracic segments, and are found very faintly marked on 

 the abdominal segments. The head is always concealed by the 

 anterior protuberance of the buckler; the antennae are almost 

 always inactive. The abdomen, often short and contracted, be- 

 comes elongated towards laying-time, and there can be easily 

 seen one, two, or sometimes three eggs, in a more or less mature 

 state. 



" The egg sometimes retains its yellow colour for one, two, or 



Fig. 13. 



Phylloxera vastatrix (J. E. Planchon).— Female specimens and their egg. a a, 

 Antennee ; b b, Horns or suckers ; c, Egg plainly visible in the body of the insect ; 

 /, Winged form of the insect. All greatly magnified. 



three days after it has bfeen laid ; more often, however, it changes 

 to a dull-grey hue. From five to eight days generally elapse 

 before it is hatched. The duration of this period depends a good 

 deal on the temperature. The quantity of eggs, and the rapidity 

 with which they are produced, are probably determined by a 

 variety of circumstances — the health of the insect, the quantity 

 of nourishment it is able to obtain, the weather, and perhaps 



