THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



be returned to their shell vial, destroyed by 

 dropping them into a jar of mineral oil, or 

 preserved for future use. 



Preserving fluid is nine parts of 95 per 

 cent alcohol to one part of glycerine. The 

 glycerine prevents drying out. In this medium 

 the colors are retained, and the specimens re- 

 main opaque as is desired for observation by 

 reflected light. A binocular dissecting micro- 

 scope is best for observing preserved material. 

 The insects, well-covered with fluid, should be 

 placed in a Syracuse dish and are best seen 

 against a v;hite background. For detailed study 

 low magnification with a compound microscope id 

 desirable (A. R. V/hiting, 1933a). A few speci- 

 mens may be placed in a drop of glycerine on a 

 slide covered with a small cover glass. Al- 

 though the glycerine clears eventually, opacity 

 will be retained long enough for careful study 

 and drawing during a laboratory exercise. Re- 

 immersion in alcohol will restore opacity, and 

 the same specimens may be used several times. 

 A pipette is useful for returning the alcohol 

 to the vials, and the insects may be picked up 

 with a camel's hair brush. 



The rearing of Habrobracon as an experimen- 

 tal animal is dependent upon many factors, the 

 most important of which is the culturing of itsi 

 host, Ephestia kuhniella. These insects show a 

 complete metamorphosis, and it is the larval 

 stage that is utilized in rearing Habrobracon. 

 The Ephestia larvae are about five-eighths of an 

 inch in length when full grown. Success in 

 rearing the moths is attained with rolled wheat 

 (Pettijohn's Breakfast Food) or untreated yel- 

 low corn meal. These cereals appear to furnish 



ao 



