E. aquilonia is an entirely dark species, apparently with a northwestern distribution. The following characters distinguish it from all other Ectromyia species known to me: tarsi entirely
dark brown to black, calyptrae and fringes blackish, wings brownish-fumose, eyes pubescent, several or more stigmatal bristles; disc of sternopleuron with
numerous stiff hairs; body velvety-black, especially in the male
Male.—Frons dull brownish-black; slightly more than twice as long as wide
(4.25:2.1); thickly covered with stiff setaceous hairs; these hairs almost as long as
the orbital and ocellar bristles, i.e., as long as the length of the third antennal
segment; about 17 inferior orbital setulae, none arising dorsad of the orbital
bristle, but, in side view, the apical portion of some hairs visible above this
bristle. Parafacial, opposite the base of the antenna, at least as wide as the ocellar
triangle; becoming less than one-half this width below; entirely dull brownishgrey
pollinose. Subgena (cheek) rather narrow, in side view not as wide (high)
as the width of the third antennal segment; bristly hairy; the oral setulae, although
arising in a uniserial row, giving the impression in side view of an upwardly
directed duster. Face, lunule, and genal areas brownish-grey pollinose. Com¬
pound eye uniformly but rather sparsely pubescent with three to four ommatidia
between any two hairs, each fine hair slightly longer than the diameter of an
ocellus. Antenna entirely black; third segment about as long as wide (1.5:1.5);
arista short, about 2.5 times as long as third antennal segment; very shortly
pubescent; thickened on the basal one-third; penultimate aristal segment about
twice as long as wide. Postocular fringe of hairs uniformly short, those adjacent
to the outer vertical bristle not twice as long as the others in the series.
Mesonotum and scutellum brownish-black, plainly dulled by a uniformly
heavy coating of velvet-like, brownish pollen. Mesonotum covered with long
erect hairs, the usual bristles being scarcely distinguishable among them; several
hairs behind the prescutellar dorsocentrals. Scutellum with five or six hairs on
the margin between the lateral and apical scutellar bristles, and about the same
number between the apical bristles; these hairs not on the disc of the scutellum
except at its extreme apex; one hair cephalad of the right lateral scutellar bristle,
in the type specimen, but usually this area bare. Notopleuron with one or two
hairs in addition to the two notopleural bristles. Epimeron with a cluster of
(stigmatal) bristles. (Five to six in the holotype). Mesopleuron and sternopleuron
densely bristly hairy on the discs; the usual strong bristles scarcely
distinguishable; sternopleuron with several hairs behind the strong sternopleural
Legs and tarsi brownish-black; front and hind metatarsi lighter brownish
from the side; preapical dorsal tibial bristles weakly developed; mid tibia with an
apical ventral thorn about as long as the tibia is wide; front femur bristly
posteriorly, mid femur with a ciliate row of posteroventral bristles; hind femur
without outstanding hairs or bristles.
Wings distinctly brownish-fumose, more intensely so anteriorly and basad.
Calyptrae greyish-brown with darker brown borders and fringes.
Abdomen broad, the dorsum broadly oval in outline; uniformly dulled by
I brownish pollen as on the thorax; last apparent segment but little longer than
the preceding one.
Genitalia (Figs. 16 and 17).—The epandrium, in lateral view (Fig. 17), less
distinctly boot-shaped than in abietum, barbara and brevistylata. The "toe"
relatively undeveloped, and the setaceous hairs arising from it shorter and less
developed than in these three species; always with two setulae on the inner
expansion of each anterior gonopophysis (Fig. 16).
Female.—In general, less pollinose and more shining than the male, particularly
on the abdomen; hairs of the frons mesonotum and pleurae shorter, hence, the
principal bristles easily distinguished.
Frons more than three-fourths as wide as long (3.75:4.5). Parafacial much
broader, i.e., about twice as broad as in the male. (This does not mean that the
parafacial is twice as wide as the female ocellar triangle.) Notopleuron without
hairs. Mesopleuron with four or five strong posterior mesopleural bristles.
Sternopleuron with one strong and one weaker sternopleural bristle in addition
to numerous hairs, one or two of these arising behind the posterior bristle.
Dorsum of abdomen mostly shining black, lightly dusted anteriorly in the
( middle. Ovipositor (Figs. 4 and 8) short as m brevistylata.
Reared from cones of alpine fir, Abies lasiocarpa (Hook.) Nutt., Douglas fir, Pseudotsuga taxifolia (Poir.) Britton, and larch, Larix laricina (Du Roi) K. Koch.