APATURA II. 



larva^ on the Plate. Init the group in nature Avould l)e compact as I have before 

 stated. I found that they fod principally at night, the leaf in the morning hav- 

 ing been eaten at one sjiot as if all had fed at the same time. When finally 

 there remained nothing Imt the patch on -which they rested, they were forced to 

 shift to a fresh leaf. From the earliest stage, the surface of the leaf about and 

 beneath these larvre was kept thoroughly clean, but just outside the grouj) was a 

 mass of excrement in a pretty regular ridge and as if it had been voided at that 

 place. It was some days before I discovered the explanation of this, by happen- 

 ing to come upon the larvas one morning when they were engaged in a general 

 cleansing. The colony was comparatively active, many of its members moving 

 about, some crawling over the backs of the rest. When a bit of frass was encoun- 

 tered by one of these last, who seemed especially deputed to act as scavengers, it 

 was seized by the mandibles, and if very small, the head and thoracic segments 

 were jerked back, and by a snap the frass was thrown some distance, at least 

 two lengths of the caterpillar. If this happened near the edge of the colony the 

 frass probably went over; if not, and it fell short, either one of the larvae on 

 which it struck seized it, or it was met bv one of the scavenQ-ers, and was ati-ain 

 snapped ofl'. until by repeating the process as often as was necessary, the obnox- 

 ious thing was gotten rid of When a considerable mass was encountered, it was 

 broken by jaws and feet, or two or three of the larvae tugged at it till it was 

 brought near the edge and toppled over. In some cases, as one of the larvae 

 voided its frass, it turned and seized it. snapping it away. Presently the colony 

 was cleansed and all its niemljers resumed their usual attitude of rest. This 

 sanitary work could only have been necessary when the larvw were in confine- 

 ment, as in natiu'e they would have rested on the under side of the leaf. 



Before the first moult took place the larva remaineil immovaljle for about two 

 days ; the skin on the second segment became swollen and nearly covered the 

 head. When the change occurred, this burst, disclosing the new head and ant- 

 lers, and the skin was speedily shullled oft' and devoured. This process of moult- 

 ing was l)y no means simultaneous throughout the colony, but Avas going on for 

 two or three days before all were changed. And the same may be said of each 

 successive moult. 



Soon after the second moult, which occurred 1st August and days tbllowing, 

 roost of the larva} began to change color, first .to pink, then to brown. In other 

 cases the change was very gradual, and the winter coat was not assumed before 

 1st September. All these at last rested on a common bed of silk web which cov- 

 ered the surface of the leaf, each with head bent under so that the fiice was in 

 same plane with the lower side of the body, the back arched, and the last seg- 

 ments appressed. But three of the larva> behaved difterently, and after having 



