308 



Habits of the Qreenliouse White Fli/ 



Tracheal system (Fig. 10). This is very simple, there being inter- 

 connected dorsal and ventral systems, with very few small branches. 

 This suggests that there may be some respiration through the skin. 

 There are two pairs of thoracic spiracles situated, one pair between the 

 anterior legs, the other between the posterior legs. Also there are two 

 pairs of abdominal spiracles, one pair on the first abdominal segment, 



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Fig. 9. Cycle of movements of 

 stylets. 



Fig. 10. Dorsal view of a mounted larva. 



the other at the sides of the vasiform orifice. All the spiracles are 

 ventral and placed upon elevations. 



In preparations to show the tracheal system, there is seen a large 

 vessel which ends suddenly in the fourth abdominal segment, without 

 small branches. It is in connection with the dorsal system (Fig. 10). 

 The larva is very small and the abdominal spiracles are in any case 

 very difficult to observe. It is my belief that this large trachea indicates 

 the presence of a spiracle which I have been unable to demonstrate 

 with certainty. There is certainly an indication of a pair of ventral 

 pores on the fourth abdominal segment. 



