MECHANISM OF FEEDING IN HEMIPTERA — QADRI 243 



alternately. At first, one mandibular stylet is thrust out and held in 

 position, then the tip of the other comes down and meets it. The 

 present writer (1949) has expressed doubt as to the validity of this 

 explanation in the Indian mango hoppers Idiocerus (Jassidae) and 

 Pyrilla (Fulgoridae). In the heteropterous bugs the views of the 

 writer find further support. The mandibular stylets of these bugs 

 appear to be adapted mainly for holding onto the tissue beneath the 

 integument. The recurved spines on the outer aspects of their apices 

 are amply suited for the same purpose. This having been achieved, 

 the rest of the work of piercing the tissue to any required depth is 

 performed by the needle formed by the interlocked maxillary stylets. 

 The hairs on the sides of the inner aspects of each maxillary stylet 

 provide a powerful mechanism for keeping the two stylets together. 

 In Anisops (fig. 8) it can easily be observed that the maxillary stylets 

 can travel to a great distance beyond the tips of the mandibles. The 

 present writer has found the same feature in Ranatra (Nepidae) and 

 Sphaerodema. The insertion of the protractor muscles directly on 

 the main shaft of the maxillary stylet and the reduction of the lever 

 furthermore prove that the maxillary stylets are indeed adapted to 

 move to a far greater distance than the mandibular stylets in which 

 protractor muscles are inserted on a well-developed lever. In fact 

 the development of the lever in the mandibular stylet restricts the 

 onward movement of the latter to a limited distance. In this connec- 

 tion it is interesting to note the length of the mandibular and maxil- 

 lary stylets ; those of Sphaerodema are obviously much longer than 

 those of Anisops. The same feature has been described in Naucoris 

 cimicoides by Becker as well as by Rawat. All these facts show 

 beyond doubt that the maxillary stylets do not confine their move- 

 ment to a distance enclosed between the two apices of the mandibular 

 stylet as held by Weber, but that they move far beyond the apices of 

 the latter. The present writer therefore holds that the mandibular 

 stylets move only to a limited distance beneath the surface of the 

 tissue to a desired depth so that the two stylets can catch the tissue 

 by their recurved spines, which perform an anchoring function. The 

 maxillary stylets which enclose the food and salivary canals move 

 down to varying depths, performing the double functions of dissolv- 

 ing the tissue by means of salivary enzymes and sucking the fluid. 

 The present view of the writer finds support from the observations 

 of Awati (1914, fig. 25) on the potato capsid bug Lygus pahulinus, 

 Awati has shown the movement of the stylets beneath the surface 

 of the leaf. His figure clearly shows that the mandibular stylets catch 



