-56 I'ROwHOPl'K'^ BI.KillT OF SUGAR-CANE. 



Goujrh (1911 C. p. 17i found a slij^ht excess of females (2,098 males to 

 2,259 females) in adults captured by hand in the fields but points out 

 that light traps had been recently used in the field which would reduce 

 the nuujber of males, and in addition the greater activity of the latter 

 sex makes them less liable to capture by hand. 



In adults caught in -.i net by sweeping the canes and grass at dusk I 

 found only HI per cent, of females but in this case the greater activity 

 of the male has an opposite effect and makes them more liable to leap 

 up into the passing net. 



The proportion of the sexes actually in the field at any moment will 

 also be influenced by the relative length of life of the two. Towards the 

 end of the brood the longer living sex (in this case the female) will 

 gradually predominate. 



ANATOMY. 

 The onl}' important studies on the anatomy of the froghopper have 

 been made by Kershaw. He describes the breathing svstem of the 

 nymph (1913 C.), the mouth apparatus of. the adult (1913 H & 1914), the 

 alimentary canal (1914), the reproductive system (1913 G.) and the male 

 genitalia (1913 D.) 



The salivanj glandu : In 1913 H he describes the mechanisui of 

 the sucking of the sap and also of the supply of saliva to the setae which 

 pierce the leaf. The salivary glands open by two flexible ducts into a 

 syringe or pump, by means of which the saliva is forced out when 

 required on to the setse of the mouth, down which it flows into the 

 wound in the plant. "It is supposed that the saliva flowing into the 

 wound made by the setae tips prevents the coagulation of the sap or aids 

 its free flow. Be this as it may, the saliva is full of enzvnies (ferments) 

 and since it is sucked back into the stomach along wi^ the plant sap, 

 it aids in digestion." 



Later (Kershaw 1914 p. 70) he says that the salivary glands differ 

 slightly in the nymph and adult. They consist of a great length of coiled 

 chitinous dnct situated entirely within the head, which he believes to 

 act as a reservoir ; and twelve tubular glands, eleven of which are longer 

 than the body and somewhat coiled or recurved in the abdomen among 

 the fat body, the twelfth is shorter and thicker and lies partly within the 

 head. The secretion of the glands appears to be neutral or faintly alkaline. 



The above descriptions are quoted in view of the possible importance 

 of the saliva in setting up the destruction of the leaf round the puncture 

 of the adult by some toxic or enzyme effect. 



The rest of the alimentary canal is described fully by Kershaw (1914) 

 including a remarkable enfolding of a portion of the mid-gut and 

 malpighian tubules by a lateral pouch at the juncture of the oesophagus 

 and mid-gut, which he considers is an arrangement for getting rid more 

 rapidly of innutritions liquid in the food in the oesophagus. 



Beproductive System : In 1913 G. p. 95 and plate on p. 104 Kershaw 

 describes the reproductive system of both sexes. In the female each 

 •ovary consists of about 20 egg tubes and each tube produces usually 

 three eggs or a probable total of 120 eggs for each female. There are a 

 pair of collcterial glands operiiug into the oviduct and a bursa-copulatrix. 



In the male there is a single accessary gland attached to each duct. 



HABITS OF ADULT. 



The adult after emergence remains inside the froth chamber formed 

 by the nymph for some hours until the chitin has hardened and the 

 -colour developed. Emergence has been noticed more frequently in 

 the early morning, but this may be due to the fact that search has most 

 frequently been made at that time. 



