The eggs are usually laid in pairs on the upper surface of a leaf of sallow, willow, or poplar. In colour these are purplish or reddish brown, shining, and finely grained; a minute depression at the top is yellowish, with a black speck at the bottom of the hollow. In its last stage the caterpillar is green, with a white or yellowish-edged purplish brown band on the back; the head is light brown margined with black and purplish behind, and the ring immediately following (first thoracic) is green margined with yellow and having two black spots on the upper part. When the creature assumes the position which Professor Poulton terms the terrifying attitude, the front part is elevated, the head is drawn back into the ring next to it, and the tails are raised and curved forward over the back (see Plate 25). Seen thus from the front the appearance of the caterpillar is certainly grotesque, and no doubt affords it some protection from its enemies. It feeds on poplars, sallows, and willows, usually in July and August, but sometimes as late as September. {63} [Illustration: FIG. 20. CATERPILLAR OF PUSS MOTH.] The reddish brown chrysalis is enclosed in a hard cocoon spun up and securely attached to the trunk or under a limb of the tree upon which the caterpillar was nourished, or upon some other adjacent thereto. I once found a cocoon on the lower rail of a garden fence. In constructing the cocoon fragments of bark and wood are worked on the exterior, but failing these the caterpillar will make use of any available material for the purpose. If enclosed in a tumbler covered with glass it will spin a transparent cocoon. Emergence from its strong pupal chamber would appear to be a difficult matter, but the caterpillar and the chrysalis both contribute something towards assisting the final efforts of the moth to escape. The caterpillar, in constructing the cocoon, is careful to make the exit end with a thinner layer than the other parts; then the chrysalis is provided with a cutting implement in the shape of a keel-like arrangement on the fore part, and with this it operates at the right time on the weak end until a breach is made; the moth breaks the head end of the chrysalis case and moistens {64} the ruptured material with a softening fluid so that the insect is able to force its way out of the cocoon; the chrysalis case remains in the cocoon. The moth is on the wing in May and June, and sometimes July. Three specimens that I reared this year (1907) from eggs found on a leaf of poplar last year, emerged on June 4th, 10th, and July 12th. They all pupated about the same time, and side by side on cork bark. I believe this species has not been recorded from the Orkneys or the Shetlands, but with these exceptions it seems to occur in more or less frequency throughout the United Kingdom. It is widely distributed in Europe, and its range extends to Siberia. In Lapland, Amurland, Japan, and North Africa it is represented by named forms.