Carpenter et al.: Mosquitoes of Southern U. S. 21 



dentists, can generally be obtained upon request. The specimens are packed 

 as follows: Set the rubber plug at the middle of the cartridge; transfer the 

 larvae to the cartridge and fill completely with preservative; insert a hypo- 

 dermic needle into the rubber stopper, allowing the opening of the needle 

 to come barely inside; push the rubber stopper, containing the inserted needle, 

 into the cartridge (as the stopper is pushed into the cartridge, the excess 

 preservative will escape through the needle) ; remove the needle. If the 

 needle is set at the proper depth, the stopper can be inserted without trapping 

 air in the tube. The collection data should be written on a small, flexible 

 card, coiled and inserted in the open end of the cartridge below the rubber 

 plug. This method of packing larvae reduces breakage of specimens and keeps 

 evaporation of the preservative at a minimum. 



Mounting Larvae. — Permanent slide mounts of larvae are often necessary 

 for study of characters used in mosquito identification. Several reliable tech- 

 niques for making mounts are discussed here. 



Chloral gum, or Berlese's medium, may be conveniently used for mounting 

 larvae since it has the advantage of being water-soluble. It has the disad- 

 vantages, however, of being very slow to harden and of discoloring and 

 crystalizing within a few years. The modification of Berlese's medium given 

 by King, Bradley and McNeel (96) is as follows: 



Distilled water 8 cc. Chloral hydrate 70 gm. 



Gum arable (dry powdered) 8 gm. Glacial acetic acid 3 cc. 



Glycerin 5 cc. 



Dissolve in the above order in a water bath and strain through muslin. 



rubber plug 



rubber stopper 



preserved larva tiypodermic needle 



Fig. 6. Method of packing mosquito larvae for storage or shipment. 



If the larva has been preserved in alcohol or formalin, it should be allowed 

 to stand in water for a few minutes to rinse, then placed in chloral gum on 

 a clean slide. An applicator stick, whittled to form a small spatula is con- 

 venient for lifting the larva without breaking hairs. The abdomen of a 

 Culicine larva should be partially severed between the 7th and 8th segments 

 with dissecting needles so that the siphon and anal segment will turn and lie 

 flat. A similar procedure should be followed with Anopheline larvae when 

 it is necessary to examine the pecten. After the larva has been properly ori- 

 ented, a clean cover slip is applied. By gently touching the cover slip with a 

 pair of forceps as it settles, shifting of the larva can usually be prevented. A 

 little practice will soon enable the technician to know how much medium to 



