sarcophaga and alijes 15 



Spreading the Genitalia. 



This indispensable operation involves just about 

 as much effort as spreading the wings of Lepi- 

 doptera, and like it, may be performed either 

 upon fresh specimens or upon dried ones that have 

 been relaxed in a moist chamber. With fresh ma- 

 terial the custom of the writer is to take a dissecting 

 needle with a minute hook or right angle at the tip, 

 hold the specimen under the low power of the binocu- 

 lar dissecting microscope between the thumb and 

 finger, and draw the forceps and inner organs as far 

 back as they will go without tearing the tissues; 

 stretching the nmscles and ligaments in this way a 

 few times, they do not retract the organs so strongly. 

 After this is done, lay the pinned fly with its side 

 against the surface of a piece of cork, by sticking its 

 pin into the edge of a second piece of cork that has 

 been attached to the surface of the first. It is then a 

 simple matter to again draw out the genitalia (under 

 the binocular) and hold them so by sticking pins into 

 the cork. Leaving the specimen to dry, a matter of 

 two or three days, finishes the process. 



Dry material will need to be placed in the relax- 

 ing jar for 24 hours, longer with very old specimens. 



Wliere time cannot be allowed for relaxing, boil 

 the specimen in water for a minute and proceed; the 

 wings will be spoiled, but the pollen of the body sur- 

 face generally comes back to its original appearance 

 better than when merely warm water is used. 



Modifications of the described method will natur- 

 ally suggest themselves. A binocular microscope is 

 not indispensable, though it is a very great advantage. 

 Professor Melander's illuminating apparatus for the 

 binocular (Jour. N. Y. Ent. Soc, xxi, 227, 1913) 

 has been used througliout the present work, and cer- 

 tainly doubles the usefulness of the microscope. 



