246 LEPIDOPTERA 



is pretty readily recognized by the dark reddisli-brown color 

 with black bands and stripings and the border including a 

 number of white spots. It deposits eggs on milkweed as its 

 host plant. These eggs hatch very shortly and the larvae 

 develop during the latter part of the summer and ])U})ate 

 and become aflults in autumn, and it is quite common in 

 October to see immense swarms of these butterflies. They 

 gather along hedge rows and on trees, sometimes appearing 

 by millions. Late in the afternoon they will cluster on the 

 branches in immense numbers. At the time of their gather- 

 ing in immense numbers they seem to have a general south- 

 erly movement and they are known to migrate at least to 

 some extent during the autumn, though the migrations 

 probably do not cover as long distances as that of birds — 

 not over 200 to 500 miles. They appear in great abundance 

 in the South in the winter. It is not possible to follow indi- 

 viduals for very great distances, but evidently they hibernate 

 in the adult stage in the South and it is pretty generally 

 believed that the hibernating individua,ls in Northern locali- 

 ties are likely to perish. Individuals that start the first 

 generation must have travelled from the South. The spring 

 individuals are frayed and give evidence of having travelled 

 some distance. The spring-appearing individuals deposit 

 eggs and from these the generation of caterpillars comes 

 that mature during midsummer. The adults appear in the 

 latitude of New York about the middle or last of July. 

 There are tw^o distinct generations for each year. The cater- 

 pillar is quite prominently banded and has some striking 

 thread-like appendages. It reaches the length of one and a 

 half or two inches and is nearly as thick as a pencil. It is 

 found particularly on the milkweed. Their pupation occurs 

 by attachment to the leaves of the milkweed or plants or 

 objects convenient or adjacent to the host plant. The pupa 

 cases are attached by a sort of spur or hook at the posterior 

 end of the body caught into a little web that has been spun 

 on the leaf. The larxjie locate on a suitable object and spin 

 a little web and then the larva contracts and the larval skin 

 splits along the back and this larval skin is held l)y the pos- 



