Swinging loosely from last summer's twigs in lilac bushes, and on such trees as wild cherry and ash, one often finds the slender cocoons of the Promethea moth (Fig. 89). We cannot help admiring the skill and care displayed by the spinner of this tidy winter overcoat. The giant silk-worm which spun it chose a leaf as a foundation. He took care to secure himself against the danger of falling by fastening the leaf to the twig which bore it by means of shining strands of silk. It is easy to test the strength of this fastening by attempting to pull it loose from the twig. [Illustration: _Fig. 89. Cocoon of Promethea moth fastened to a twig with silk._] The moths which come from these cocoons do not always look alike, yet they are all brothers and sisters. The brothers are almost black, while the wings of the sisters are light reddish brown, with a light gray wavy line crossing the middle of both wings. The margins of the wings are clay-colored. On each wing is a dark velvety spot. The adults emerge in spring and are most often seen in the late afternoon. Their flight is more spirited than that of the Cecropia, which moves very sedately, as becomes a giant. [Illustration: _Fig. 90. Cocoon of Promethea, cut open lengthwise to show the valve-like device at upper end through which the adult moth pushes its way out._] The caterpillars of this species, the young Prometheas, feed during the summer on leaves of wild cherry, ash and other trees. They grow to be about two inches long, and are distinguished from others by their pale bluish green color and yellow legs. They also have rows of wart-like elevations on their backs, some black and shining, four of a bright red and one large and yellow near the hindmost end. * * * * * The life of these giant insects is divided into four distinct stages: the egg, deposited by the adult moth usually on or near the food plant; the larva, or caterpillar stage, when most of the eating and all the growing is done; the pupa, passed inside the cocoon woven by the larva; and the adult, a winged moth. The life-cycle or generation is one year, the winter being passed in the pupa stage. The insect lives but a short time in the adult stage and the egg stage is but two or three weeks. Most of the summer is devoted to the caterpillar phase of its life. These creatures are entirely harmless. They seldom appear in numbers sufficient to make them of economic importance. LEAFLET XV. A TALK ABOUT SPIDERS.[19] BY J. H. COMSTOCK. [19] Nature-Study Quarterly, No. 9: Leaflet 22. May, 1901. [Illustration]