32 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.64. 



Ninth ubclominal segment with or without two, fine, short caudal setae. 



First abdominal spiracle about as large as the mesothoracic spiracle and 

 much larger than rest. 



Eighth abdominal tergum with spiracle-bearing chitinous hook, or a low, 

 soft elevation. 



Second, Third, and Fourth instaks : Body ovate or cylindrical, often slightly 

 or, in Nemognatha, strongly curved. 



Head-capsule and mouthparts thinly chitinized. 



Prothorax, never with strongly chitinized shield. 



First, Second, and Third exuvia shed. Fourth and Fifth exuvia not shed ; 

 fifth instar covered with one exuvium and sixth instar with two closed exuvia. 



Sixth exuvium completely shed, except in tribe Nemogtiuthini in which it is 

 adherent to inside of exuvium of fifth instar. 



First to Sixth instaks parasitizing on bees, feeding on the egg and honey 

 of a single bee cell or, in the Nemognathini, feeding on tlie contents, egg, larva, 

 and honey of two cells. 



First instar carried by bee host; attached to bee hair by mandibles alone. 



Fourth instar always sedentary. 



KEY TO TRIBES AND GENERA. 



1. First instar with mandible carrying 6 to 8 teeth. Sixth instar not ad- 



herent to fifth exuvium. Sixth exuvium shed 2 



First instar M'ith mandible carrying 2 to 3 teeth. Sixth instar either not 

 adherent or adherent to exuvium of fifth instar 5 



2. First instar with mandibles carrying 7 to 8 teeth ; anterior nasal margin 



obtuse, almost truncate ; head comparatively short and broad ; tarsus 

 conico-falcate, long and slender with two, not equally long, slender tarsal 

 setae, none of which are as long as tarsus ; spiracle-bearing elevation 

 either short or well developed. Fifth instar with thin skin; gradually 



becoming triangular-prismatic 3 



First instar with mandible canning 5 or 6 teeth ; anterior nasal margin sub- 

 conical, not truncate ; head comparatively elongate ; medio-dorsal suture 

 on thoracic segments varying ; tarsus variable in form, always with well 

 developed tarsal setae; spiracle-bearing elevation well developed, and 

 as long as ninth abdominal segment. Fifth instar more or less rigid ; 

 never deformed 4 



3. First instar with mandible with 8 teeth; spiracle-bearing elevation low, 



rather soft, much shorter than length of ninth abdominal segment; one 

 well developed, almost ventral tarsal seta ; medio-dorsal suture on all 

 thoracic segments complete; one pair of fine and very short caudal 



setae SITARINI-HORNIIDES. 



Genus Hornia. 

 First instar with mandible with 7 teeth ; spiracle-bearing elevation well de- 

 veloped and hook-shaped SITARINI-HORNIIDES. 



Genus Allendesalazaria. 



4. First instar with" spathulate tarsus; both tarsal setae almost as long as tar- 



sus SITARINI-STENORIIDES. 



Genus Stenoria. 

 First instar with conico-falcate tarsus ; tarsal setae somewhat shorter than 



tarsus SITARINI-TRICRANIIDES. 



Genus Tricrania. 



