MOSQUITOES (cULICIDjE). 



81 



and thrust the pin, which now carries the disc, through the centre 



of the thorax, between the bases of the legs, 

 until the tip of the pin projects a little 

 beyond the dorsal surface of the thorax* 

 [d) ; invert the disc, and thrust a No. 16 or 

 an ordinary pin (e) through the disc near 

 the margin for the purpose of carrying both 

 disc and specimen. The next and last thing 

 to be done is to arrange the legs and wings 

 as far as possible — i.e. the wings must be 

 made to project at an angle from the body, 

 and not allowed to remain closed, and the 

 legs must be disposed symmetrically on the 

 card disc. These operations must be per- 

 formed as gently as possible with the help of a needle mounted in 

 a handle, and care must be taken that hairs and scales are not 

 rubbed off in the process. Proceed in much the same way in 

 pinning specimens to show the ventral and lateral surfaces. 



Preservation of Larv^ and Pup^. 



Specimens of larvse and pupse should always be preserved, especially 

 when it is possible to breed some of them out, or otherwise to 

 determine the species to which they belong. They should be killed 

 and kept in alcohol or formol.f If in alcohol, it should be about 

 60 per cent, strength. 



Of formol a 4 per cent, solution (i.e. one part of ordinary com- 

 mercial 40 per cent, solution to nine parts of water) is quite strong 

 enough for killing and preserving. 



Larvse and pupse (whether preserved in formol or alcohol) should 



* Should it be found impracticable to proceed in the manner here prescribed, 

 owing to the difficulty of making the specimen lie in the required position on 

 its back, it may be pinned in the ordinary way through the middle of the 

 thorax from the dorsal side ; in this case, however, the specimen must be 

 pinned jxr&t (i.e. before it is mounted on the card disc) ; it should be drawn two- 

 thirds of the way up the pin, and the latter should tiien be thrust through the 

 disc, holding tlie pin with the forceps below the specimen ; mount the disc on 

 a long pin, as in the first method. 



t Otherwise known as formaldehyde or formalin. 



