HELEOMYZID FLIES NORTH OF MEXICO—GILL 583 
half the height of the posterior bristle; buccal setae in 2 or 3 irregular 
rows. 
Thorax yellowish orange; dorsocentral bristles becoming weaker 
anteriorly, especially in the male (see ““Remarks’’ below) ; sternopleuron 
with 1 strong bristle in upper hind corner and with setae covering the 
remainder of the sternopleuron, longer hairs between the coxae; 
thorax otherwise similar to A. flavotestacea (Zetterstedt) ; legs yellowish 
orange; wings with brownish clouding (sometimes very faint) along 
posterior crossvein and at ends of longitudinal veins; abdomen yellow 
to reddish orange, posterior margins of segments often much darkened. 
Lzeneru.—7.0-11.0 mm. 
DistrRiBpuTIon.—South Dakota, Minnesota, Iowa, Illinois, Michi- 
gan, Indiana, Ohio, Arkansas, Tennessee, Georgia, North Carolina, 
West Virginia, Virginia, District of Columbia, Maryland, Pennsylva- 
nia, New Jersey, New York, Ontario, Quebec, Massachusetts, Ver- 
mont, New Hampshire, Maine; May—September. 
Remarxks.—Banks (1926) used the variety name angustifrons for a 
series of specimens which he observed were different from the typical A. 
helvola (Loew). The chief difference was that in the typical A. helvola 
(Loew) the anterior dorsocentral bristles of the male are very much 
weaker than the posterior pair of bristles, whereas in the angustiforms 
series these anterior bristles are not so distinctly weakened. The 
mesonotum of the angustifrons series was described as having shorter 
hairs than the typical A. helvola (Loew), the front of the head as 
being narrower, and the total body size smaller. 
I have examined all the types involved and concur in the observa- 
tions on the mesonotal chaetotaxy. | determined the ratio of the 
length of the front to the width on all the specimens. In the two 
types of A. helvola (Loew), the ratios were 0.74 and 0.75; in the types 
of angustifrons Banks, the ratios were from 0.76 to 0.84. 
Despite these differences in the type specimens, there appears to be 
enough intergradation among specimens in general to make it unwise 
to designate distinct subspecies at this time, particularly inasmuch as 
it is difficult to correlate these morphological differences with geo- 
graphical populations. 
Amoebaleria caesia (Meigen) 
FIGURE 80 
Helomyza caesia Meigen, 1830, p. 56. 
[?] Leria mustelina Robineau-Desvoidy, 1841, p. 261. 
Blepharoptera caesia (Meigen), Loew, 1859, p. 59.—Schmitz, 1909, p. 85. 
Leria caesia (Meigen), Schiner, 1864, p. 29.—Rondani, 1867, p. 127.—Pandellé, 
1901, p. 350. 
Amoebaleria caesia (Meigen), Czerny, 1924, p. 134; 1927a, p. 40. 
