2S4 INSECTS OF MASSACHUSETTS. 



each ring, beginning with the fourth. The prickles are exceed- 

 ingly sharp, sting very severely when the insect is handled, and 

 produce the same kind of irritation as those of the nettle. When 

 young, these caterpillars keep together in little swarms. They do 

 not spin a common web, but, when not eating, they creep under a 

 leaf, where they cluster side by side. In going from or returning 

 to their place of shelter they move in regular files, like the pro- 

 cessionary caterpillars (Lasiocampa processioned) of Europe, a 

 single caterpillar taking the lead, and followed closely by perhaps 

 one or two in single file, after which come two, side by side, 

 close upon the heels of these creep three more, the next rank 

 consists of four, and so on, the ranks continually widening behind, 

 like a flock of wild-geese on the wing, but in perfectly regular or- 

 der. When about half grown they disperse, and each one shirks 

 for himself. At the age of eight weeks they get to their full size, 

 in the meanwhile moulting their skins four times, and finally 

 measure two inches and a half or more in length. At this age 

 they leave off eating, crawl to the ground, and get under leaves or 

 rubbish, which they draw round their bodies to form an outer 

 covering, within which they make an irregular and thin cocoon, 

 of very gummy brown silk, that has almost the texture of thin 

 parchment. As soon as their cocoons are finished, the insects 

 are changed to chrysalids, in which form they remain throughout 

 the winter, and in the following summer, during the month of 

 June, or beginning of July, they come out in the winged or moth 

 state. The scientific name of these moths is Saturnia Io*. Un- 

 like those of the genus Attacus, they sit with their wings closed, 

 and covering the body like a low roof, the front edge of the un- 

 der wings extending a little beyond that of the upper wings, and 

 curving upwards. The two sexes differ both in color and size. 

 The male, which is the smallest, is of a deep or Indian yellow 

 color ; on its fore-wings there are two oblique wavy lines towards 

 the hind margin, a zigzag line near the base, and several spots so 

 arranged on the middle as to form the letters A H, all of a pur- 

 plish red color; the hind-wings are broadly bordered with pur- 



* Io, a priestess of Juno, in Greece, afterwards became the wife of Osiris, the 

 king of Egypt, and received divine honors under the name of Isis. 



