99 



tween tlie radius and the media ; this is termed the spurious 

 vein. 



Wing of Culex. — The wing of a mosquito is used as an 

 example of the venation of the midge-Hke flies. In these 

 the number of the branches of the radial sector is reduced in 

 away different from that seen in the families previously stud- 

 ied. Compare with the Asilid, the Bombyliid, and the Sceno- 

 pinid. 



THE WINGS OF LEPIDOPTERA. 



As the wings of Lepidoptera are covered with scales, it is 

 difficult to determine the nature of their venation without 

 specially preparing them for this purpose. After a student 

 has become familiar with the type of venation characteristic 

 of the order, he can usually determine the course of any 

 particular vein by putting a drop of chloroform on the part 

 of the wing to be examined ; this will render the veins more 

 distinct for a few seconds. Or the scales can be removed 

 from a small part of the wing with a small artist's sable 

 brush. But when a very careful study of the venation of a 

 wing is to be made, it should be bleached and mounted on a 

 card or on a glass slip, in order that it may be studied with 

 a compound microscope. The following is the method of 

 bleaching wings : — 



1. Remove the wings carefully so as not to break the fren- 

 ulum if there be one ;* it is well to remove the patagium 

 first. f 



2. Dip the wings in alcohol in order to wet them. 



3. Immerse them for an instant in hydrochloric acid (muri- 

 atic acid). Use for this purpose dilute acid, one part acid to 

 nine parts water. 



* The frenulum is a strong spine or bunch of bristles borne by the hind wing 

 at the humeral angle in most moths. 



t The patagia are scale-like appendages at the bases of the fore wings. 



