386 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loa 



the frontal vitta and the elongate frontal triangle. The third anten- 

 nal segment of the males is not enlarged. The eye may be setulose, 

 as it is in Phytobia (Icieromyza) pollinosa (fig. 87) . The wing is rela- 

 tively long and slender (fig. 86) as compared to the wings in the sub- 

 genera Phytobia (fig. 60), Poemyza (fig. 77), and Dizygomyza (fig.81). 

 The larva of Phytobia (Icteromyza) longipennis is the only one known 

 from the subgenus. The anterior spiracle has two small bulbs and is 

 very small. Each posterior spiracle of the third stage or full grown 

 larva is long, ventrally directed, sclerotized, acuminate, and bears 

 about 20 very small bulbs in a single row. Such a highly modified 

 spiracle compares favorably with the unusual and diverse types found 

 in the subgenera Poemyza and Dizygomyza and supports the close re- 

 lationship shown by the adults of the three subgenera. 



Key to the described species of Phytobia (Icteromyza) 



1. Maxillary palpus yellow; femora distally broadly yellow for a distance sub- 



equal to one-third the femoral length 2 



Maxillary palpus black; femora distally narrowly yellow for a distance sub- 

 equal to the femoral diameter capitata 



2. Eye setulose; third antennal segment yellow pollinosa 



Eye practically bare; third antennal segment mostly brown or black. 



longipennis 



Phytobia (Icteromyza) capitata (Zetterstedt) 



Agromyza capitata Zetterstedt, Diptera Scandinaviae, vol. 7, p. 2760, 1848. 

 Dizygomyza {Icteromyza) capitata (Zetterstedt), Hendel, in Lindner, Die Fliegen 



der palaearktischen Region, fam. 59, p. 52, 1931 (figures of head and wing),— 



de Meijere, Tijdschr. Ent., vol. 84, p. 15, 1941. 

 Agromyza genualis Melander, Journ. New York Ent. Soc, vol. 21, p, 261, 1913. 

 Agromyza coloradensis Malloch, Ann. Ent. Soc. Amer., vol. 6, p. 297, 1913. 



This Holarctic species is large, with a wing length of 2.5 to 3.5 mm. 

 The maxillary palpus is black and the femora are distally yellow for a 

 distance equal to the femoral diameter. A front view of the head 

 shows the form of the lunule and frontal triangle (fig. 85). De 

 Meijere found an adult of this species on the stems of Juncus sp. and 

 surmised that the larvae mined in Juncus spp. Dizygomyza (Icter- 

 omyza) capitata is northern in distribution but extends down the 

 Sierra Nevada mountain chain into southern California. It also 

 occurs in Oregon, Washington, Idaho, Montana, Utah, Colorado, 

 North Dakota, Michigan, Illinois, Maine, and Ontario. 



Phytobia (Icteromyza) longipennis (Loevr) 



Agromyza longipennis Loew, Berliner Ent. Zeitschr., vol. 13, p. 48, 1869 (Centuria 

 viii. No. 90). — Melander, Journ. New York Ent. Soc, vol. 21, p. 255, 1913. — 

 Malloch, Ann. Ent. Soc. Amer., vol. 6, p. 296, 1913. 

 This species is smaller (2.5 mm. in wing length) than Phytobia 



(Icteromyza) capitata, has the palpus yellow, and all femora distally 



