SUMMER MEETING. 



81 



through the cavity, and the slitted labrum, which encloses the more delicate 

 organs and fits down over the slit in front, near the insertion of the tube. To 



Fig. 1. 

 Plant Lon.se, or Aphis, showing mouth organs. 



get access to the sap, it is generally believed that this beak is thrust into the 

 tissue of the plant, and some who have been troubled with these pests may 

 have wondered why plants badly infected do not show the punctures, at least 

 when the parts are carefully examined with a compound microscope — the beak 

 of the greenhouse Aphis, being quite large and thick. The truth is that 

 the beak of the Aphis is not inserted in the tissue, as has been supposed. 

 The extremity is simply placed upon the surface of the epidermis, and with 

 the exceedingly fine, hair-like mandibles, the epidermal cells are punctured, the 

 rich juice of the parenchyma is reached, and by suction it is drawn through 

 the tube, passed into the aesophogus, and thus transferred into the stomach, 

 and distributed throughout the body. The mandibles being infinitesimal in 

 character, the wound made by them is not readily distinguished, even by the 

 aid of the compound microscope. Tbe loss of so much nourishment, however, 

 soon tells upon the health and vigor of the plant, and in a little while the 

 leaves begin to curl up, turn yellow, and drop off. Many of the leaves that 

 remain are so weakened that they are attacked by some fungus growth, and 

 with vegetable and insect life both preying upon its tissues, the plant at last 

 succumbs, unless some saving feature is in time introduced to restore it. 



Diminutive insects, as the Aphides are, their depredations would be compara- 



11 



Fig. 2. 

 Winged Aphis. 



Fig. 3. 

 Apterous Aphis. 



