The Fouk-lined LEAP-Bua. 233 



The insect reaches its fifth and last nymphal stage (Fig, 8), the pupa 

 of some authors, in from thirteen to fifteen days after leaving the egg. 

 The duration of this stage is from four to five days, and the nymph 

 measurigs 5.5 mm. (.21 inch) in length when the final or fifth moult 

 occurs at which the adult insect appears.* Thus the nymphal stage of 

 the insect is passed in from seventeen to twenty days. 



The adults first appeared this year about June 13. This agrees with 

 most of the recorded dates of their first appearance. Figure 3 repre- 

 sents the typical marking of the adult. Considerable variations occur 

 besides the sexual one pointed out in discussing the appearance of the 



* Dr. Lintner has watched this moult and described it in detail. He says: 

 " The change from the pupa to the perfect insect was made in so short a time, 

 that although more than a hundred examples underwent their transformation 

 in a glass jar upon my table where they were frequently examined, yet in onlj"^ 

 one instance was the operation detected. It proved so interesting, particularly 

 in the attendant gradual change of color, that it was watched and the follow- 

 ing notes thereof taken. 



When first discovered the pupal integument had split upon the back and 

 separated so as to show the larger part of the thorax of the inclosed insect, 

 the basal poi'tion of- the wings and the intermediate scutellum . The charac- 

 teristic and conspicuous black marks pertaining to maturity were entirely 

 absent — the only shades observable being orange, yellow and white; the 

 thorax was pale yellow, the scutellum light yellow with its lateral angles 

 orange; the wings were white. In this condition the insect rested for a few 

 minutes, with the terminal half of its wings still encased in their sheaths, and 

 with no movement other than a tremulous motion of the feet . It then turned 

 itself around for a few times and moved several steps over the leaf, when it 

 took position with its head directed downward, its front pair of legs holding to 

 to the leaf and the others detached. Slowly the abdomen was withdrawn from 

 its incasement and the colorless wings from their sheaths . Soon the yellow 

 stripes of the wings began to appear and insensibly to deepen. As yet there 

 was no indication of the black stripes traversing the thorax and wings, or of 

 the black of the membraneous wing tips. 



In 25 minutes fi-om the observed commencement of the transformation (at 

 1 o'clock as noticed ), the wing tips had fully expanded . The time occupied in 

 the disengagement from the puj^al case was not noted ; it could not have varied 

 much from five minutes. At 1 h. 15 m., there were indications of the black 

 stripes in a duskiness of color. At 1 h, 40 m. , the lines had deepened to a leaden 

 hue and the antennae were dark. At 2 o'clock, aU the stripes, the small spot 

 towards the wing tip, and the tip, had become blackish, and the bands on the 

 legs were showing. When next observed, at 3. o'clock, the stripes were glossy 

 jet black, and the mature coloring throughout had been assumed. 



While change of color frequently attends insect moultings, and usually to a 

 greater or less degree the larvel moults of the Lepidoptera, it is rare that so 

 marked a change as that above noted, ranging from white to black, can be 

 observed, and in so brief a time." 



30 



