418 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



species without crossvein m-m in the wing. It may be separated from 

 P. orbitalis by the yellow head, antenna, pleura, and legs. The 

 mesonotum is yellow with three light reddish brown vittae and vein 

 Mi+2 ends at the wing tip. E. M. Hering collected the greenish blotch 

 mines on leaves of Populus deltoides Marsh, in Ontario and he identified 

 adults in the Canadian National Collection from Ottawa, Ontario. 

 G. E. Shewell kindly presented me with six adults and six larvae. 

 He reports that this species suddenly appeared in large numbers for 

 the first time in 1956. 



13. Genus Pseudonapomyza Hendel 



Pseudonapomyza Hendel, Arch. Naturg., Abt. a., vol. 84, p. 115, 1920. 



Pseudonapomyza belongs to the Phytomyza group of genera but is 

 most closely related to Phytagromyza in having the orbital setulae 

 reclinate (fig. 136). The species of Phytagromyza are so diverse that 

 all of the Pseudonapomyza characters but one are to be found among 

 one or more of the Phytagromyza species. Pseudonapomyza may be 

 separated from Phytagromyza by having crossvein m-m basad of 

 crossvein r-m and appearing to be the basal section of M3+4 (fig. 135). 

 The wings of Phytagromyza species have m-m distal to r-m (fig. 134), 

 or absent. 



There are three very similar species in the world. Pseudonapomyza 

 atra is Holarctic, P. lacteipennis is Nearctic, and P. spicata (Malloch) 

 is found on Formosa and thi'oughout Micronesia and Hawaii. P. 

 spicata may be separated from the other two by the black tarsi, 

 shining mesonotum, and the presence of both the inner postalar and 

 intraalar setae. All three species have one upper-orbital, three or four 

 lower-orbitals, the thu'd antennal segment strongly angulate (fig. 136), 

 three dorsocentrals, and the wing as described and illustrated (fig. 

 135) . The larvae of two species, P. atra and P. spicata, mine the leaves 

 of grasses and have a row of elongate spines on each body segment. 



Key to the described species of Pseudonapomyza 



1. Tarsi dark brown or black; mesonotum subshining, slightly gray pollinose, 



one intraalar seta and no inner postalar atra 



Tarsi with basal four segments j'ellowish, distal segment dark brown; meso- 

 notum dull, bluisli pollinose, no intraalar and one inner postalar. 



lacteipennis 



Pseudonapomyza atra (Meigen) 



Fliytomyza atra Meigen, Systematische Beschreibung der bekannten europaischen 



zweifliigcligen Insekten, vol. 6, p. 191, 1830. 

 Pseudonapomyza atra (Meigen), Hendel, in Lindner, Die Fliegen der palaeark- 



tischen Region, fam. 59, p. 302, 1932 (figures of head and wing). 

 Phytomyza acuticornis Loew, Wiener Ent. Monatsschr., vol. 2, p. 78, 1858. 

 Phytomyza nitidula Malloch, Proc. U. S. Nat. Mus., vol. 46, p. 151, 1913. 



