Mesonotum. Normally 3 strong post- 
sutural dc, not infrequently 2 or 3 
smaller anterior ones, presutural, if 
present, little stronger than acr, 
these irregularly in 6 rows, prsc 
approx, equal to dc 3. 
Wing. Length from 2.5 mm in male to 3 
mm in female, C ending abruptly just 
beyond end of R 4+5, last section of 
M 3+4 0.67 length of penultimate, 
inner crossvein distinctly before 
midpoint of discal cell. 
Color. Frons matt black, ocellar 
triangle and bases of orbital bristles 
distinctly shining; antenna black; 
lower orbit and parafacial normally 
conspicuously shining, occasionally 
less so; mesonotum and abdomen shining 
black; legs entirely black; wing 
unusually pale, R veins dark, normal, 
M veins white, virtually colorless; 
squama and fringe silvery white. 
Male genitalia. Aedeagus with medial 
section rising abruptly from base of 
distiphallus (fig. 364), basal 
sclerites bending gradually (fig. 365) 
toward distiphallus complex; sur- 
stylus angular, with row of about 5 
short, stout bristles along inner 
margin but not extending to lower 
corner (fig. 366); sperm pump with 
large blade and long narrow base. 
Host/early stages. Unknown but larva 
certainly a grass feeder. 
Holotype m. , Utah, Salt Lake City, 
6.V.39 (G. F. Knowlton and R. L. 
Janes); paratypes 3 f., same data; 3 
f., Cache Junction, 20. VII. 13 (H. R. 
Hagen); 1 f., Promontory, 25.V.52 (G. 
F. Knowlton); 1 f.. Green Canyon, 
Cache Co., 25-27. VII. 64; 1 f.. Cache 
Co., Mendon Cold Springs, 3. IX. 65; 
(both W. J. Hanson); Colorado, Boulder 
Co., Boulder, 5,500 ft, 1 f., 5. VI. 61 
(B. H. Poole). Holotype in USNM, 
paratypes in CNC, KAS, and USU. 
Remarks. This species closely re- 
sembles and is closely related to A. 
ambigua (= niveipennis Zett.). The 
contrasting color of the R and M veins 
is distinctive, and there are slight 
but distinct differences in the 
genitalia (see particularly figs. 364, 
368). 
Agromyza varifrons Coquillett 
(Figs. 354-356) 
Agromyza varifrons Coquillett, 1902: 
189. Holotype female from District 
of Columbia in USNM. 
The food plant of this distinctive 
species, Celtis laevigata , was first 
recorded by Spencer (1966c). Empty 
leaf mines were common but local in 
Arkansas and Mississippi in May 1979, 
and two other State records are also 
recorded here. 
The leaf mine is an irregular linear 
blotch, most frequently following the 
leaf margin (fig. 356). One empty 
leaf mine found at Hot Springs, Ark., 
18.V.79 (KAS) can scarcely be 
associated with A. varifrons . It is a 
more regular blotch toward the center 
of the leaf blade and possibly 
represents an undescribed species. 
New records. 
Arkansas, Garland Co., Hot Springs, 
empty leaf mines on Celtis 
laevigata , 15- 18. V. 7 9 (KAS and GCS), 
in USNM and KAS. 
Kansas, Douglas Co., Natural History 
Reserve, Lawrence, 1 m. , 28. IV. 56 
(J. G. Chillcott), in CNC. 
Mississippi, Washington Co., Experi- 
mental Forest, Leland, empty leaf 
mines, 11.V.79 (KAS), in KAS. 
Texas, Kerr Co., Kerrville, 1 m. , 
5. IV. 56 (J. F. McAlpine ) , in CNC; 
San Patricio Co., Welder Wildlife 
Reserve, nr. Sinton, 1 f., 
19-23. III. 65 (J. G. Chillcott), in 
CNC. 
Agromyza vockerothi Spencer (new 
to U.S.A.) 
(Figs. 441-443) 
Agromyza vockerothi Spencer, 1969a: 
60. Holotype male from Nova Scotia 
in CNC. 
269 
