8 



BULLETIN 1453, U. S. DEPARTMENT OF AGRICULTURE 



NATURE OF INJURY TO CURED MEATS 



The injury to cured meats which results from cheese-skipper in- 

 festation is usually deep-seated. This is in contrast to the work of 

 other ham pests such as the red-legged ham beetle (Necrohia rufipes 

 DeGeer), which usually burrows near the surface in the soft fat or 

 just beneath the hide, and the larder beetle (Dermestes lardarius L.), 

 which is also typically a surface feeder. The favorite starting place 

 for skipper infestation is at the butt end of newly smoked hams and 

 shoulders. Here, where the soft muscles and the connective tissue 

 are exposed in cross section, are ideal feeding areas, the muscles often 

 being somewhat separated, a condition which encourages penetra- 

 tion by the maggots. In hams entrance is effected frequently 



Fig. 1. — Cross section through middle of a dry-cured ham badly injured by feeding of 

 larvae of PiopJiila casei. The outer layer of fat at the upper left has collapsed over 

 the eaten-out cavities. Much reduced 



around the exposed bone on the inside, and less often at the hock end 

 where the string passes through, in the small but deep holes left by 

 the inspector's trier, and in small cuts. In the usual well-advanced 

 infestation the insects are found at the center of the meat, in the 

 vicinity of the joint of the bones. 



In cured meat, putridity does not usually become marked until the 

 infestation is rather old and consequently fouled by larval excreta. 

 New colonies of the larvae, even though extensive, have little offensive 

 odor, but the cavities of hams infested for some time give off a strong 

 moldy-sour odor similar to that of old brood comb. 



Murtfeldt (53, p. 172) noted the lack of putrefaction in infested 

 hams, but Sakharov (67) has given data to show that in infested 

 fish the skipper maggots have a symbiotic relationship with an un- 

 determined putrefactive organism. 



