THE BLUEBOTTLE FLY. 81 



The action of these flaps may be studied under the 

 microscope. For this purpose the common house fly is 

 better, being smaller. Proceed as follows : Wet one side 

 of a large crystal of granulated sugar, place it on a slide, 

 and let it dry fast. Place the slide on the stand of the 

 microscope, blocking up one edge at a decided angle. 

 Focus on the crystal of sugar with the lowest power of 

 your instrument. Take your apparatus thus prepared 

 into a room, or other place where there are many hungry 

 flies, and wait for one to alight on the slide, and apply the 

 opened leaves or flaps of the end of its proboscis to the 

 sugar. Focus carefully, and record your observations on 

 the action of this part. 



Examine a bluebottle fly that has been freshly killed 

 in a cyanide bottle. 



External Anatomy. Observe the general contour of 

 the body, the shortness of the abdomen, and the speciali- 

 zation of the thoracic region. 



Note the shape of the head, the freedom of its movements, 

 the position and size of the eyes and ocelli. 



Find the short antennae. Remove one, being careful 

 to get it off entire, and examine it with the microscope. 

 Find in it six segments, as follows: 



1. A small subquadrate first or basal segment, bear- 

 ing on one side, near its base, four conspicuous bristles. 



2. A roundish second segment, bearing one stout, 

 straight bristle, and a number of smaller ones. 



3. A large, oblong segment, much the largest in the 

 antenna, its surface sprinkled with minute pits and hairs. 

 This segment at first appears to be terminal, but it is in 

 fact much produced laterally. 



4. Two minute segments, attached near the base of the 

 third segment, and forming a sort of pedicel for the ter- 

 minal segment. 



NEED. ZOOL. 6 



