Genus Brenthis Hübner (the Little Fritillaries)
Small or medium-sized butterflies, closely resembling those of the genus Argynnis. The chief difference is that in Brenthis only the first subcostal nervule branches off before the end of the cell, while in Argynnis the first and second are thus given off; palpi not so stout as in Argynnis; the basal spur of the median vein of the fore wing, found in Argynnis, is wanting in Brenthis. Eggs subconical, twice as wide as high, truncated, vertically ribbed. Caterpillars like those of Argynnis, but smaller, and often lighter in color, feeding on violets. Chrysalis pendant, about 0.6 inch long; two rows of conical tubercles on back.
Sixteen species are found in North America, all of which but two are subarctic or occur on high mountains.
(1) Brenthis myrina (Cramer), Plate XVII, Fig. 1, ♂, upper side; Fig. 2, ♂, under side (The Silver-bordered Fritillary).
Well depicted in the figures we give. Expanse 1.40-1.70 inch. Eggs pale greenish yellow. Caterpillar, when fully grown, about 0.87 inch long, dark olive-brown, marked with lighter green, and covered with spiny, fleshy tubercles. Chrysalis yellowish brown marked with darker brown spots, some having a pearly lustre.
Ranges from Nova Scotia to Alaska and southward as far as the mountains of the Carolinas.
(2) Brenthis montinus Scudder, Plate XVII, Fig. 3, ♀, under side (The White Mountain Fritillary).
Upper side fulvous, the wings at base darker than in B. myrina, the black markings heavier. Hind wings below much darker than in B. myrina, the silvery spots being quite differently arranged, the most conspicuous being a bar at the end and a round spot at the base of the cell of the hind wing. Expanse, ♂, 1.50 inch; ♀, 1.75 inch.
A small species living on the summit of Mt. Washington, New Hampshire, where a little colony has survived the glacial epoch, when the northeastern parts of the United States were covered with glaciers, as Greenland is to-day.
(3) Brenthis bellona (Fabricius), Plate XVIII, ♂ (The Meadow Fritillary).
The only species of the genus, except B. myrina, found in the densely settled portions of the continent. Easily distinguished from myrina by the absence on the under side of the wings of the silvery spots, which make the Silver-bordered Fritillary so attractive. It is generally found upon the wing in the late summer and the fall of the year. In Pennsylvania it may be found when the asters are in bloom.
Common throughout Canada and the northern United States as far west as the Rocky Mountains and as far south as the Carolinas. Expanse 1.65-1.80 inch.