158 PROCEEDINGS OF TWENTY-SIXTH FRUIT-GROWERs' CONVENTION. 



just over the ends of the breathing grooves, from which proceed long, 

 delicate pencils of wax. The arrangement of the wax glands upon the 

 body will doubtless be found to be one of the most available means of 

 distinguishing between the various species. 



The Transformations. — The transformations of these insects are 

 accomplished by a series of moults. The insect at the time of moulting 

 becomes suddenly active, not walking about the leaf, but keeping its 

 beak inserted in and retaining its position on the leaf. This activity con- 

 sists in bending the body up and down and contorting it to some extent, 

 apparently in the effort to disengage itself from the old skin which it is 

 about to discard. Soon there appears a split along the middle line 

 toward the front end of the insect, terminating posteriorly by a trans- 

 verse one not far from the region of the anterior breathing grooves. Out 

 of this rupture the insect crawls, leaving the old skin upon the leaf. 

 The freshly moulting insect soon finds a place not far off, and establishes 

 itself. The old skin, which is only held by the beak, sooner or later 

 becomes disengaged from the leaf, and falls off and disappears. Before 

 the final moult, at which the insect becomes adult, there has been a 

 great change taking place in all the internal organs of the body, as well 

 as by the development of wings and legs, so that when this moult is 

 accomplished the insect escaping bears no resemblance to its former self. 



The Adult Insect. — The body of the perfected insect is slender, the 

 legs long, and the newly formed wings very large and conspicuous. 

 Every part of the body is covered with a w^hite powdery secretion, 

 making it snowy white. As the white-fly rests upon the leaf the wings 

 lie like a roof over the body, in such a position as to make the insect 

 appear very broad and robust. The insect is very active, flying better 

 than the members of either of the most nearly allied families. As in the 

 case of plant-lice, the winged form is the chief or only ordinary means 

 of distribution from plant to plant. Some species may be seen in the 

 air in swarms, at times in company with plant-lice. 



Like the plant-lice, also, these insects continue to feed after they 

 obtain their wings, but it is during the earlier stages of their lives that 

 they do the most damage to vegetation. 



The White-Fly of the Vine. — Our most injurious species is the 

 one that attacks grapevines. This insect has never been described, nor 

 has any mention of it been made, in any publication upon the insects 

 of the vine. As with all white-flies, the injury done by this insect is 

 that which is caused by its fluid excretions. This, in the case of the 

 present species, seems to be somewhat poisonous to the under surface of 

 the leaves, producing an effect somewhat like that following the work of 

 the red spider. On the upper side it is usually less evident, except 



