A short time after the caterpillar's skin has thus been cast off the chrysalis takes on a brownish color which as is so often the case is likely to vary somewhat according to the tint of the surrounding surfaces. This is doubtless a protective device and helps the insect to escape attack by birds during the long period of exposure. For this butterfly passes through the winter only in the chrysalis condition, and the larva which went into the chrysalis in September does not come out as a butterfly until the following May or June. There are, however, two broods of the butterflies in the North and at least three in the South. As the adults live for about two months and there is considerable variation in the periods of their development it happens that one can find these Black Swallowtail butterflies upon the wing almost any time in warm weather, either North or South. =The Giant Swallowtail= _Papilio thoas_ The largest of our North American butterflies is a magnificent insect with a wing expanse of some four inches and with a rich coloring of black and yellow more or less suffused with greenish or bluish iridescence that gives it a striking beauty as it flies leisurely about from flower to flower or stops to lay an egg upon some bush or tree. The tails are long and expanded toward the tip, their prevailing color being black with a broad splash of yellow near the end. In a general way we may say that the upper wing surface is black marked with two bands of orange-yellow, while the under surface is yellow marked with two bands of black. (_See plate, page 64._) The Giant Swallowtail is a tropical species which is abundant throughout the Southern states and during recent years seems to have been gradually extending its northern range. It is now commonly found as far north as forty-two degrees latitude, from Nebraska eastward. In New England it is occasionally taken in Connecticut, Massachusetts, and even in Maine, but its appearance in this region is exceptional. In the orange-growing regions of the Southern states the caterpillars of this butterfly feed freely upon the leaves of citrus fruits and they are often called "orange puppies" or "orange dogs." Probably their curious appearance and their habit of resting for long periods upon leaf or twig gave rise to this name. In the region indicated the life-history of the insect may be summarized thus: