THE TRIBE OF THE CRESCENT-SPOTS 137 



manner as during the time when the mammoth and the mas- 

 todon were Hkely to invade its haunts . {See plate ^ page 129.) 

 The Baltimore is probably the most local in its distribu- 

 tion of any of the butterflies found throughout Canada 

 and the Northern states. It is to be looked for only in 

 peat bogs and swamps, and it has a remarkable unity in 

 its life-history whether it be found in northern Canada or 

 as far south as West Virginia. The butterfly itself is 

 rather large, measuring a little more than two inches across 

 its expanded wings and being colored with an unusual 

 combination of fulvous and yellow upon a black back- 

 ground. It is present as a rule only from about the first 

 of June to the middle of July. The eggs, in bunches of 

 from one hundred to four hundred, are laid upon the 

 leaves of the plant commonly called snake-head or turtle- 

 head {Chehne glabra) . They do not hatch for nearly three 

 weeks; then the little caterpillars emerge together and 

 usually each eats a little of the empty egg shell. They 

 are then likely to form a thin web over the under surface 

 of the leaf beneath which they remain as a small company 

 feeding upon the succulent green tissue. A little later 

 they are likely to begin the construction of a miniature 

 nest by spinning a silken web over the young leaves at the 

 top of the plant. From this time on this silken nest serves 

 as their home, and they utilize it almost as effectively as 

 do our familiar American tent caterpillars the nest which 

 they make in the forks of the wild cherry tree. The 

 Baltimore caterpillars often wander more or less from their 

 tent-like home but they generally come back to feed as 

 well as to moult. If the nest is injured by wind or rain, all 

 the caterpillars turn out to repair it and as the need for 

 new food supplies arises they also unite to enlarge the 



