228 NATURE-STUDY REVIEW [12:5— May, 1916 



old skin ; row after row of the tubercles appearing as they gradually 

 worked the skin off towards the caudal end of the body. Mrs. 

 Comstock says that the first molt takes place about four days after 

 they hatch ; but our caterpillars did not molt for nearly a week and 

 a half. Perhaps confinement had something to do with their 

 being so slow. At first great numbers died. They seemed to 

 shrivel and dry up. Then we began dipping the leaves upon which 

 they fed into water, and from then on they seemed to thrive. 

 After the first molt they were a dull yellow or orange with black 

 tubercles. After the second molt, which occurred in about two 

 weeks, they were a clearer, brighter yellow and the tubercles were 

 larger ; those down the middle of the body on the second and third 

 segments were red ; the others yellow. Those on each side of the 

 caterpillar and on the first segment were black or a steel blue. 

 The third molt occurred about a week and half later, when the 

 caterpillars appeared with a greenish blue body; the large tuber- 

 cles were still red, and those down the center, yellow, as in the last 

 molt ; but those on the first segment and on the sides were now a 

 beautiful turquoise blue. In another week they molted for the 

 fourth time. Now the large tubercles were orange color and during 

 this and the preceding stage the caterpillars ate voraciously and 

 grew very rapidly. Some of them measured over three inches in 

 length and were as large through as a man's thumb. They ate for 

 two weeks and then began to spin. 



It was very interesting to watch them. They began by stretch- 

 ing a few supporting strands of silk ; then they fastened a very loose 

 net work to these supports; and next began the spinning of the 

 outer layer of the cocoon. In a very short time they were so 

 covered that the rest of the work went on unseen and we were 

 unable to determine the length of time required to complete the 

 cocoon. 



In the spring we had cut open some of the punctured cocoons 

 and found them to be really wonderful pieces of work. They are 

 composed of three walls or layers of silk, the first very tough and 

 thick; the second made up of loosely woven threads; and the 

 inner one thin and smooth as the inside of a milk weed pod. The 

 cocoon makes a winter home which protects the pupa perfectly 

 from both wet and cold. The cecropia always spins along the side 

 of a branch; and at one end the threads are spun lengthwise, form- 

 ing an opening through which the moth works its way out. 



