34 STRUCTURE OF CERTAIN DIPTEROUS LARViE. 



transverse striae, the area on fifth segment smaller than the others; 

 the anal area shows two large, smooth, prominent, submedian 

 tubercles; there are no tubercles outlinhig tlie stigmal field; the stig- 

 mal plates are contiguous, each with three short, straight slits 

 directed toward those of opposite plate; these slits are much shorter 

 and broader than in Rhagoletis. 



This species, the orange maggot, is sometimes found in Mexican 



oranges. 



ORTALID^. 



The larvae of the ortalid fhes are rather more slender than those of 

 Musca; the two great hooks are. distinct; the anterior spiracles have 

 about ten lobes; the ventral fusiform areas are distinct, but the 

 lateral rather weak; the tip of body ends in two slight processes 

 bearing the posterior stigmal plates, each with three short slits. 



Most of the species occur in places where they are not apt to be 

 swallowed by man, but the onion maggot, and a few other forms, may 

 occasionally be taken in food. 



Euxesta tJiomse Loew. 



(Plate III, figs. 53, 59.) 



Body smooth, slender; two great hooks; two distinct papillae on 

 the bilobed head; segments from 5 on each with distinct fusiform, 

 swollen area on ventral base, each area with several transverse 

 ridges; lateral fusiform areas fairly distinct; anal area not swollen, 

 and no tubercles; tip of body rounded and smooth, without tubercles; 

 each stigmal plate on an elevated black base, each plate with three 

 short slits and a button, but indistinct; nine lobes in the anterior 

 spiracles. 



In ear of corn from Texas. 



A similar ortalid from tomatoes in Florida has but five lobes in the 

 anterior spiracles, and the slits on the posterior spiracles are more 

 nearly on the outer edge. 



Tritoxa Jlexa Wied ( ? ) 



(Plate III, figs. 44^6.) 



Slender; head truncate, with two small papillae; two great hooks; 

 anterior spiracles with ten lobes ; segment 5 and beyond each with a 

 swollen, fusiform area on ventral base, each area with several ridges 

 in front and behmd, leavmg a smooth space in the middle; a faint 

 transverse Ime on middle of ventral segments; lateral fusiform areas 

 visible, but not prominent; anal area with a low swollen lobe each 

 side, no tubercles; a few fine ridges above and below anal area; last 

 segment rounded, smooth, no tubercles; stigmal plates on low ele- 



