THE STRUCTURE OF CERTAIN DIPTEROUS LARV^ 

 WITH PARTICULAR REFERENCE TO THOSE IN 

 HUMAN FOODS. 



INTRODUCTORY. 



There is a considerable number of flies whose larvae either regu- 

 larly or occasionally live in substances used by man as food. The 

 great majority pass through the mtestinal tract without our knowl- 

 edge, for most of them cause little or no trouble. But sometimes 

 with patients in hospitals or asylums, or in private practice, the 

 physician discovers these maggots, and often suspects them of causing 

 the malady or weakness of his patient. 



Many such specimens have been sent to entomologists, but owing 

 to the fact that no one had studied these forms, their characters were 

 little understood, and the identifications have not been of much 

 value. Mo§t of these larvae belong to a few closely related families of 

 flies that were formerly covered by the name Muscidae. The arrange- 

 ment of the flies has been the subject of much diverse opinion, while 

 the knowledge of the larvaB is very fragmentary. 



For these reasons Dr. Howard, Chief of the Bureau of Entomology, 

 suggested that the writer make a study of larvae belonging to these 

 groups m the collections of the Bureau of Entomology and the 

 National Museum, so that in the future a more cojTect determmation 

 might be made of the larva? that are quite frequently sent to this 

 bureau. 



OCCURRENCE. 



When we consider that these dipterous larvae occur m decaying 

 fruits and vegetables and on fresh and cooked meats; that the blowfly, 

 for example, will deposit on meats in a pantiy; that other maggots 

 occur in cheese, oleomargarine, etc., and that pies and puddings m 

 restaurants are accessible and suitable to them, it can readily be seen 

 that a great number of these maggots must be swallowed by persons 

 each year, and mostly without any serious consequences.^ Besides 



' "Taking ovprythinc; into considoration, \vc doubt whother. out of ten thousand cases, where the larvfp 

 of two-winged (lies have existed in considerable numbers in the human intestines, more than one single 

 case has been recorded in print for the edification of the world by competent entomological authority." 

 Walsh, Amer. Ent., vol. 2, p. 141, 1870. 



