Botanobia darlingtoniae (Diptera: Chloropidae)

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Locality

Mount Eddy, near Sisson, Siskiyou County, California.

Description

The eggs of this fly are deposited singly on the inner wall of the leaf, above the mass of insect remains and often well up toward the orifice of the pitcher; they are not strongly adherent and are frequently wedged under the fine elastic hairs which clothe the leaf-wall. From one to twenty eggs may be found in a leaf, but even when most numerous, they do not appear to have been laid in groups or clusters, and the maximum number is attributable to the visits of more than one female to the same leaf.

Egg—Cigar-shaped, roundedly-pointed at one end, the other with a short cylindrical or collar-like cap of less diameter than the body of the egg; obscurely and shallowly wrinkled longitudinally; white, opaque, pearly, faintly polished, under 100x finely punctate; length 0.9mm and greatest diameter 0.2mm.

Larva—Slender, cylindrical, tapering and strongly retractile anteriorly; white, translucent, smooth, but segmentally with narrow ventral fusiform areas marked by short acute granules, coarser beneath and fading out laterally; black cephalo-pharyngeal skeleton with two great hooks visible through the translucent anterior segments; anterior spiracle inconspicuous, few-lobed, concolorous, not protruded; the two posterior dorsal stigmata in form of eve-armed crosses surmounting prominent dome-shaped processes, the inner arm of each cross partially obliterated by the circular extremities of the tracheal tubes; anal lobes low, smoothly rounded; extreme length about 5mm. The larvae are active, moving feely about among the insect remains and climbing up the vertical wall of the pitcher in search of food or when ready to pupate.

Puparium—Shorter and stouter than the larva and hardening to a dull bronzy-brown color; flattened ventrally where in contact with the leaf; segmentation not distinct; first visible segment flattened, transversely wrinkled, darker in color; anterior spiracles small, hand-like, slightly projecting, black; second segment low-arched, the succeeding segments more highly arched until posteriorly they become almost cylindrical; the anterior segments on their lateral edges above have a well marked longitudinal angular depression, outside of which the margin is produced and rounded; the terminal dome-shaped processes bearing the shrunken larval stigmata are prominent but less regularly shaped than in the larva, concentrically wrinkled, and the dorsal area immediately preceding them is also roughened and transversely wrinkled; length 3.5mm; pupation usually occurs among the dry insect remains or on the inner wall of the leaf often well up toward the orifice or even in the hood; pupal stage (in August) eight to ten days.

Imago ♀♂—Black, head and thorax not shining, surface roughened and thinly white-pollinose; mesonotum and scutellum studded with short abbreviated dark stripe above each wing base; abdomen dark brown above (almost black when dry), broad, flattened, slightly glossed, microscopically punctate, finely haired; legs yellow and black.

Eyes—widely separated, dark bronzy brown, finely pubescent; ocellar tubercle slightly raised, usually paler by denser pollinosity, the anterior ocellus inclined on its front edge; no frontal triangle, but a prominent slightly sunken narrowly oval dark marking, laterally pale-bordered, extending forward from anterior ocellus; orbits pale gray, those of the front sometimes tinged with brownish-yellow; the front produced, broadly snout-like, over the base of the antennae, this produced and rounded area being pale dull brownish-yellow, with several rows of recumbent and convergent hairs; a pair of post-ocellar bristles, erect, converging, their points crossed; these, with a pair of erect and divergent outer verticals, are the strongest of the head bristles, which are black, usually from black bases.

Antennae—large, directed laterally, appressed to head; the first joint hidden, the second broadly bell-shaped, yellow often partially obscured with dark and with a marginal row of spur-like hairs from black bases; the third joint much enlarged, longer than broad, rounded apically, basally on inner side dull salmon-yellow, sometimes ferruginous, the remainder dark purplish gray, almost black, and both joints thinly and finely white pollinose; arista black and tapering, shortly and sparely haired, the cheeks produced in advance of the face, in color pale dull brown sometimes varying to and always merging into the gray of the posterior orbits; cheeks conspicuously marked with black dots which form the bases of recumbent forward-pointing hairs; a pair of well-differentiated brown vibrissal hairs; the black dots continued in a regular row around the posterior orbits. Face black; clypeus and well defined median carina pale. Mesonotum with a narrow black meidan stripe (a dull black area destitute of pollen) extending to scutellum, two similar lateral stripes abbreviated slightly in advance of scutellum and two short dark markings above the wing bases. On each side two humeral bristles, one to two anterior and two posterior notopleurals, two post alar and one pre-scutellar; the uppermost anterior notopleural weak and apparently sometimes missing.

Scutellulm—broad, rounded, almost semicircular in outline, discally flattened, in color and texture like the mesonotum, but laterally broadly darker; marginal scutellars black, four pairs distinguishable; median pair best developed, their points approaching or crossed.

Halteres—long, club-shaped, white, unmarked, their stems sometimes darkened to almost black.

Wings—transparent, unmarked, iridescent, their surface roughened with minute evenly distributed rasp-like hairs; veins dark brown; anterior edge closely set with short bristly hairs directed obliquely forward, gradually merging into the short fine even-length fringe; the costal thickening to V1 plus 2 (4th longitudinal); axillary incision very deeply out, its extremity rounded, separating from the rest of the wing a long finger-shaped axillary lobe which is edged interiorly with long black hairs; second and third costal divisions equal, each twice as long as first; hind cross-vein twice its length from small cross-vein; III4 plus 5 and V1 plus 2 (third and fourth longitudinal) parallel.

Femora and tibiae—set with stiff hairs; femora black usually shortly tipped with ferruginous yellow; tibiae yellow, broadly black-banded beyond the middle; tarsi yellow, terminal joints darkened to almost black; middle and hind legs with short tibial spurs.

Abdomen—as stated that of the ♂ rounded posteriorly, of the ♀ with an extruded hypopygium which is slender, tapering, fineliy haired, furcated and appressed, a long bristle terminating each fork; lateral and ventral posterior margins of segments gray-edged.

Average length dry specimens, ♂ 2.1mm; ♀, 2.4mm; minimum and maximum of twelve examples 1.9mm and 2.8mm.

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