Silver-bordered Fritillary (Brenthis myrina). Expanse 1¾ inches. Known by its small size and a marginal row of silver spots on the under side of each of the wings, and with many other silver spots scattered over the under surface of the hind wings.
Meadow Fritillary (Brenthis bellona). Expanse 2 inches. Easily known by the absence of silver spots on all the wings. The wings are long in proportion to their width.
THE TRIBE OF THE CRESCENT-SPOTS
The members of this tribe have the following combinations of characters: scaly antennae, with a short stout club some three times as long as broad, and a pair of slender palpi in which the terminal joint is only about half as long as the middle one. There may or may not be a slight ridge running lengthwise of the naked part of the antennal club.
Although more than fifty distinct species belonging to this tribe have been found in North America, very few of these are distributed through the eastern part. Only four are so abundant and widely distributed that they need be treated of here.
Baltimore Checker-spot
Euphydryas phaeton
To the naturalist those islands in the seas which are remote from the mainland have long been of especial interest. The life upon them is likely to show the results of many generations of living under unique conditions. The plants and animals are generally distinctive, many of the species having characteristics which differentiate them markedly from those upon the mainland. They show in a thousand ways the effect of isolation and so are of especial value when one attempts to determine the results of unusual conditions upon living things.
In a somewhat similar way the peat bogs or sphagnum swamps which occur here and there over a large part of North America are of especial interest, because in a way they are biological islands in which the conditions of a long past age are preserved until the present. These nearly always occur in a little valley surrounded on all sides by hills. Here the water has collected originally into a pond or lake, which has been gradually filling up through the growth of peat mosses and a special set of other plants that develop in such situations. One can still find many stages in the process. In some bogs the surface will be practically covered, although the water beneath may still be so abundant that the matted moss quakes as one walks over it. Sometimes such bogs are really dangerous because the walker may drop through to the water beneath. In most of the bogs, however, the little lake is nearly filled but shows the surface over a small area.
The conditions in these peat bogs have changed little since civilization began. They are relics of an earlier era which have come down to us as types of conditions that once existed very generally. The plant life is unique and consists almost entirely of forms which are found practically nowhere else. There are comparatively few animals living in these peat bogs and all of these are likely to be of especial interest. Among the insects none is more remarkable than the Baltimore Checker-spot butterfly which has several peculiarities that differentiate it from the other members of the group. It seems to have come down to us unchanged from a far remote past and to be living its tranquil life to-day in precisely the same manner as during the time when the mammoth and the mastodon were likely to invade its haunts.
The Baltimore is probably the most local in its distribution of any of the butterflies found throughout Canada and the Northern states. It is to be looked for only in peat bogs and swamps, and it has a remarkable unity in its life-history whether it be found in northern Canada or as far south as West Virginia. The butterfly itself is rather large, measuring a little more than two inches across its expanded wings and being colored with an unusual combination of fulvous and yellow upon a black background. It is present as a rule only from about the first of June to the middle of July. The eggs, in bunches of from one hundred to four hundred, are laid upon the leaves of the plant commonly called snake-head or turtle-head (Chelone glabra). They do not hatch for nearly three weeks; then the little caterpillars emerge together and usually each eats a little of the empty egg shell. They are then likely to form a thin web over the under surface of the leaf beneath which they remain as a small company feeding upon the succulent green tissue. A little later they are likely to begin the construction of a miniature nest by spinning a silken web over the young leaves at the top of the plant. From this time on this silken nest serves as their home, and they utilize it almost as effectively as do our familiar American tent caterpillars the nest which they make in the forks of the wild cherry tree. The Baltimore caterpillars often wander more or less from their tent-like home but they generally come back to feed as well as to moult. If the nest is injured by wind or rain, all the caterpillars turn out to repair it and as the need for new food supplies arises they also unite to enlarge the tent. This habit of working together for the common good is very suggestive of the similar habits of the American tent caterpillars. Doors for going in and out are left in the tent during its construction.