LARVAL TAXONOMY OF THE TROGINAE IN NORTH AMERICA 11 



70-percent ethyl alcohol for storage. Best results with KAA were 

 obtained with recently moulted larvae. Late third stage larvae of 

 Omorgus usually shriveled instead of expanding when placed in KAA. 

 Best results with boiling were obtained with larvae which had ceased 

 feeding but had not yet become prepupae. The digestive tract of 

 actively feeding larvae often burst when the larvae were boiled, re- 

 leasing the gut contents into the hemocoel. This produced a blackish 

 specimen, whereas the desired state is straw yellow to white. 



During fixation the anal area of most specimens becomes greatly 

 expanded, exposing the lining of the rectum. The pattern of the 

 sclerotized areas on this inflated, membranous lining of the rectum is 

 quite different for Trox and Omorgus (figs. 50 and 52). 



Rearing of Immature Stages 



The method used for rearing the larvae was adapted from that 

 previously used by Ritcher.^ Individual rearings were canned out with 

 all species that could be confused on the basis of external morphology. 

 This necessitated the sexing of specimens, since only two species are 

 sexually dimorphic. The specimen was inactivated with carbon dioxide 

 and placed under a binocular stereomicroscope. A pair of No. 5 

 jeweler's forceps was used to open the urogenital orifice so that the 

 genitalia could be viewed. After sexing, the females were placed in 

 separate rearing containers. 



The rearing containers varied in size from a pint jar to a gallon jar 

 depending on the size of the species. The jar was about two-thirds 

 filled with damp, screened sand overlaid with food. The food consisted 

 of a mixture of cow hair, deer hair, sheep's wool, rabbit hair and skin, 

 and pheasant, quail, and dove feathers and skin. Great care had to be 

 exercised to insure that the food source was free of insecticide. The 

 jar was wrapped with a black plastic sleeve that could be removed to 

 check for eggs or larval burrows against the sides or bottom. The 

 jars were capped to keep out pests such as dermestids and tineids and to 

 maintain a high level of humidity. 



The eggs and larvae were removed at about 14-day intervals to 

 individual 2-ounce salve boxes. A representative portion of the Fi 

 generation was preserved as larvae. The suspected identity of the fe- 

 male was then confirmed by dissection of the male genitalia of adults 

 of the Fi generation. 



Individual larvae were reared in salve boxes filled with damp, 

 screened sand with a small amoimt of food on one side. The develop- 



^ Personal communication with Dr. P. O, Ritchcr wherein he described the 

 method he devised for the rearing of Trox larvae after observing how easily Dr. 

 M. A. Czizier reared the larvae of one Southwestern species. 

 285-935—68 2 



