THE CANADIAN HORXicULTUniST. 173^ 



become fully expanded, scattered sparsely on some of the leaves near 

 the ground, and about the size of an ordinary pea. Within this gall 

 the parent louse may be found busily laying little yellow eggs of an 

 elongated oval form, and nearly the one-hundredth part of an inch in 

 length. The appearance of these eggs is shewn in fig. 12, at c, highly 

 magnified. The mother-louse herself is about four-hundredths of an 

 inch in length, usually spherical in form, and of a dull orange color. 

 The forms marked by the letters y, g, and A, in fig. 12, shew the mother- 

 louse ; f being a side view, g shewing the back, and h the under side. 

 The skin of this insect is shagreened or minutely granulated, and 

 furnislie-J with rows of minute hairs. Within this cup or sack she 

 continues to deposit her eggs until they are all laid, from two to five 



hundred in number,. and then dies and dries up. 



« 

 In from six to eight days the eggs burst, and the young lice come 



forth. These are little six legged creatures, with two antennaj, and 

 supplied "with an instrument for puncturing and sucking up the juices- 

 of the leaves. They are represented at letters a and h, fig. 12, the 

 imder side being shown at a, the sheath of the pumping apparatus, 

 extending nearly the entire length of the insect, and the upper side or 

 back being seen at 5. These young lice are quite active, and creeping' 

 out at the mouth of the sack in which they were born spread themselves- 

 over the vine, seeking the young and tender leaves near the ends of 

 the shoots. Having found a suitable place for their future operations 

 they settle down for life, and using their proboscis, (which consists of 

 three elastic, wiry hairs, so fine that when they are united they form a 

 thread so small that it can scarce be seen with a very powerful 

 microscope, and yet so sharp that they easily puncture the outer 

 surface or parenchyma of the leaf,) they thrust it into the leaf and 

 commence to pump xip and feed upon its juices. This puncture, and 

 the irritation kept up by the insect, causes the under side of the leaf 

 to thicken, and gradually to form the sack or cup shewn at d, fig. 12. 

 into which the- louse settles as the sack forms; increasing also in size 

 Tantil it presents the appearance shewn at ^ and 7i, fig. 12. Having 

 become fully grown, she is also full of eggs, which without any impreg- 

 nation from the male louse are fertile. These eggs she lays in quick- 

 succession until the gall is filled with them. This production of living, 

 issue without assistance from the male is called parthenogenesis, and 

 i^g not confined to this insect only, but belongs also to other forms of" 



