Tibia, tarsi, or antennal segments paler, at least 
slightly yellowish brown 2 1 
21 (10). Frons brownish orange 22 
Frons darker, black or dark brown 23 
22 (21). 1 ors-- A. ambrosivora Spencer 
Synopsis. Frons distinctly projecting above eye; 1 
reclinate ors, 4 or 5 inclined ori, all slender; 
gena deeply extended at rear, 0.25-0.33 height 
of eye; mesonotum shining black, with 2 strong dc 
and 2 or 3 beyond, differentiated from acr but 
short; acr numerous, in at least 8 rows; legs with 
femur black but knee yellowish, tibia and tarsus 
paler, brownish; squama and fringe silvery white; 
wing length 2.7-3 mm; male genitalia with aedeagus 
having long, paired tubules, uniformly curving, 
fused at base, separating apically (fig. 391). 
Host/Early Stages. Ambrosia artemisiifolia , 
probably Artemisia douglasiana (Calif.). Several 
larvae frequently feeding together to form black- 
ish leaf mine that extends from apex of pinnately 
divided leaves toward midrib; pupation externally, 
puparium brown, posterior spiracles each with 3 
bulbs; larval mouth parts with 3 teeth (fig. 392). 
Distribution. California; Canada. 
References. Spencer, 1969a: 35; 1981: 109. 
^ ors-- A. virginiensis Spencer 
Synopsis. Frons not projecting above eye; 2 ors, 3 
ori; gena 0.33 height of. eye; all antennal seg- 
ments pale, orange; mesonotum shining black, with 
4 pos tsutural dc, acr in 8 rows; femora black, 
knees paler, tibiae and tarsi brownish orange; 
wing with all veins pale; squama whitish yellow, 
fringe silvery; wing length in male 3 mm, costa 
extending only weakly to vein M 1+2, last section 
of M 3+4 short, 0.5 length of penultimate; male 
genitalia with aedeagus (fig. 393) having 
dis t iphallus exceptionally long, paired tubules 
sinuate, fused to slightly beyond midpoint. 
Host/Early Stages. Unknown. 
Distribution. Virginia. 
Reference. Spencer, 1977c: 237. 
Remarks. This species generally resembles and is 
obviously closely related to A. ambrosivora but 
different arrangement of orbital bristles and 
longer aedeagus justify treating it as 
distinct . 
23 (21). Mesonotum predominantly matt, blackish gray or 
gray 2 4 
Mesonotum shining black 26 
24 (23). Gena broad, at rear 0.33 height of eye — — 
7 A. reptans Fallen 
Synopsis. Frons distinctly projecting above eye 
(fig. 394), about 1.5 times width of eye, with 2 
ors and 3 (sometimes 2) ori; gena extended at 
rear, 0.33 height of eye; 3d antennal segment 
brownish black, sometimes paler, distinctly brown; 
64 
