1010] Life History of Pterodontia 313 



Of the American species the pupa of Oncodes costatus Loew is 

 described by Malloch (12). The description was made from a 

 single pupal exuvium. In most respects the pupa seemed to be 

 similar to that of Pterodontia but differs in having five spiracles ; 

 the anterior four are on prominent protuberances. The crest 

 of barbed spines is also wanting in this species. 



THE ADULT. 



Female. — ^(Fig. 1) Head spherical and small in proportion to the 

 thorax. Eyes contiguous, large, black, and densely clothed with long, 

 black setas. Ocelli three in number. Antennae inserted ventrad of the 

 compound eyes; they consist of three segments, the third of which 

 bears three or four terminal setse. The mouth-parts are obsolete. 

 Thorax large, mesonotum piceous and shining; scutellum light yellow or 

 sometimes light brown. Ventral parts of thorax dark brown. The 

 entire thorax is clothed with long, black hairlike setae. Legs pale 

 3^ellow except the femora which are somewhat darker yellow or brown- 

 ish. Tegulae large and brownish in color. Wings slightly clouded, 

 membrane undate, veins dark yellow or brown. Venation as shown in 

 Figure 3. The toothlike projection near the distal end of the costal 

 margin is wanting in the female. Abdomen large, globular and inflated. 

 First abdominal segment black or brownish. Second abdominal segment 

 yellow or testaceous and with the cephalic margin black; in some indi- 

 viduals this segment has a median triangular black spot. The third 

 segment in most specimens is entirely yellow or testaceous; however, 

 a few specimens have a median, black, triangular spot on the cephalic 

 margin. The remaining segments are yellow or testaceous. Ventral 

 surface of abdomen dark brown. The entire surface of the abdomen is 

 clothed with long, black, hairlike setcC. The length varies from 4 to 8 

 mm. with an average of 6.5 mm. taken from a series of twenty-six 

 females. 



Male. — The male differs from the female in the following points: 

 Thorax broad and more robust than that of the female. Four posterior 

 femora black. Wing veins j^ellow, toothlike projection on the costal 

 margin prominent (Fig. 3). Second abdominal segment shining black. 

 Third segment testaceous and with a large median rectangular spot. 

 Fourth segment testaceous but sometimes with a median oval black 

 spot. The remaining segments are testaceous (Fig. 2). Length 6 to 9 

 mm., average about 7 mm. 



A closely allied western species of this genus has been 

 described by Osten Sacken (17). This species, Pterodontia 

 misella, so closely approaches Pterodontia flavipes Gray (6) that 

 it is sometimes difficult to determine to which species a variety 

 may belong. Williston (19) says concerning P. misella O. S.: 

 "I have several specimens of this species from Washington 



