BOJV TO COLLECT MOSQUITOES 221 



rest. On the wing it cannot be caught, even with a deli- 

 cate net, without rubbing or leg-breaking. If a mosquito 

 lights upon your hand, or upon a twig or a leaf, or upon 

 a wall of a room, it is quite easy, especially if it be en- 

 gaged in sucking blood, to cover it adroitly with the vial. 

 It rises almost instantly, and the mouth of the vial is 

 plugged with a plug of absorbent cotton. A drop of 

 chloroform on the cotton will stupefy the specimen almost 

 immediately and another drop will kill it. 



The specimen may be kept permanently in the vial and 

 when studied, if the study goes no farther than an exami- 

 nation of the coarser characters in an attempt to determine 

 the species, it will often suffice gently to slide it out 

 upon a sheet of white paper and examine it with a power- 

 ful hand lens. With the one-quarter inch achromatic 

 triplet lens made by different firms I have found it pos- 

 sible to distinguish all of the generic and specific char- 

 acters, even down to the teeth of the tarsal claws. This, 

 however, is difficult to persons who are not accustomed 

 to the use of high-power hand lenses, and in such in- 

 stances one must break off a tarsus and mount it upon a 

 slide in glycerine or Canada balsam for examination 

 under a compound microscope. 



It is not advisable to mount adult mosquitoes bodily on. 

 slides in any medium whatever. They should not be pre- 

 served in alcohol or formalin, but should be kept dry in 

 vials. Of course they will rattle around somewhat and 

 there is danger that the legs and the antenna) will be lost ; 

 therefore, if they are moved from the vial after the col- 

 lecting and killing, into pill boxes with cotton, they can 



