POSSIBLE STRIDULATLNG ORGAN TN THE MOSQUITO. 371 



the wing vibrations — is unexplained by this view. It is, however, easily explicable if 

 such a stridulating organ as we have described at the base of the wing in Anopheles 

 maculipennis be found in other Diptera and in Hymenopterous insects. 



On Plate we have thought it well to figure the upper surface of the halter as 

 seen under a high magnification. The drawing shows the hinge on which the halter 

 quivers, the basal-papilla-plate, as Weinland * calls it, and the same author's ' skapale '- 

 papilla-plate of the upper side. The papillae of the basal-papilla-plate are continued on 

 to its under surface, and only a few are shown in our drawing. 



There is little doubt that the main functions of the halteres is that of balancing and 

 orientating the insect. They may, however, have some secondary function ; in some 

 flies they are known to vibrate with extreme rapidity. It is just possible that in these 

 rapid vibrations the papillae of the concave surface rubbing against those of the convex 

 basal plate may produce a note. As long ago as 1764, von Gleichen-Russworm t 

 observed that when the halteres of the common house-fly are removed, the amount of 

 the buzzing is diminished. This, however, in all probability, is due to the diminished 

 activity of the wings. On the other hand, Mr Stanley J. Gardiner informs us that 

 he has noticed that mosquitoes still continue to give forth a faint note even when their 

 wings are quite at rest, and this may possibly be caused by the halteres. 



* Zeitschr. uriss. Zool., li., 1891, p. 55. 



t Geschichte der gemeinen Stubenfliege, Nuremberg, 1764. 



[Explanation. 



TRANS. ROY. SOC. EDIN., VOL. XL. PART II. (NO. 18). 3 k 



