Carpenter et al.: Mosquitoes of Southern U. S. 15 



or pure carbolic acid. Specimens that are kept in pill boxes should be stored 

 in large cans or jars containing napthalene or paradichlorobenzene. 



Preparing Male Terminalia for Study 



For making specific identifications and for studying relationships between 

 the difiFerent species of mosquitoes, the examination of male terminalia is 

 invaluable. Any medium used for mounting larvae may also be used for 

 mounting terminalia. It is often not desirable, however, to make a perma- 

 nent mount but merely to examine the specimen in water or gylcerin, and 

 then store in 70 to 80 per cent alcohol for future reference. 



To prepare terminalia for study, carefully clip off the apical fourth of 

 the abdomen with sharp scissors or forceps and place in a small casserole 

 containing a 10 to 20 per cent solution of potassium hydroxide. Heat the 

 solution to near the boiling point, and then transfer the terminalia to a 

 beaker of water and allow to rinse for several minutes; then place it in a 

 drop of water or gylcerin on a slide and examine with a dissecting microscope. 



To mount in chloral gum, transfer the specimen with a dissecting needle 

 from water to a drop of the mounting medium on a clean slide. Remove the 

 superfluous abdominal segments from the terminalia proper, orient it with 

 the dorsal side up and extend the dististyles. Since the terminalia of the 

 genus Ctilex have stout basistyles, either these structures should be dissected 

 loose at their bases and laid flat, or the cover glass should be blocked up with 

 small pieces of glass. In the Anophelines, the anal lobe and the ninth tergite 

 often obscure characters of the phallosome; therefore it may be necessary 

 to dissect these structures away from the rest of the specimen, but they 

 should be left in the same field. Anopheline terminalia should be mounted 

 flat so that the leaflets of the phallosome will straighten out and be easily 

 seen. A specimen may tend to shift out of position when a cover slip is 

 applied, but this can usually be prevented if slight pressure is exerted on the 

 cover slip with a pair of forceps as it settles into place. 



Chloral gum is a convenient medium to use for mounting terminalia, but 

 the mount usually lasts for only a few years. Specimens mounted in chloral 

 gum are extremely easy to remount, however, which is a point not to be 

 overlooked if a detailed study of the specimen in different positions is 

 desired. For a more permanent mount, however, Canada balsam, clarite, 

 creosote-balsam, or Euparal are preferred (see methods for mounting mosquito 

 larvae) . 



If creosote-balsam is used, leave the specimen in 80 per cent and 95 per 

 cent alcohol for 5 minutes each, and in absolute alcohol for 30 seconds; then 

 transfer with a dissecting needle to a clean slide on which has been placed a 

 drop of the creosote-balsam medium. If the standard Canada balsam method 

 is followed, the same procedure as above can be used, except that a 2- or 

 3-minute clearing step must be introduced between the absolute alcohol and 

 final mounting medium. The authors prefer creosote U. S. P., oil of winter- 

 green, or clove oil over xylene as clearing agents since they do not cause the 

 specimens to become brittle. 



