TRANSFORMATIONS OF INSECTS. 11 



The full grown caterpillar becomes restless, and 

 leaving the plant, seeks some sheltered situation in 

 which to pupate. " It first spins," says Dr. Harris, 

 " a little web or tuft of silk against the surface where- 

 on it is resting, and entangles the hooks of its hind- 

 most feet in it, so as to fix them securely to the spot • 

 it then proceeds to make a loop, or girth, of many 

 silken threads, bent into the form of the letter U, the 

 ends of which are fastened to the surface on which 

 it rests on each side of the middle of its body ; and 

 under this, when finished, it passes its head and 

 gradually works the loop over its back, so as to 

 support the body and prevent it from tailing down- 

 wards. Within twenty -four hours after it has taken 

 its station, the caterpillar casts off its caterpillar skin, 

 and becomes a chrysalis, or pupa (Plate I, d) of a 

 pale green, ochre-yellow, or ash-gray color, with two 

 short ear-like projections above the head, just below 

 which, on the back, is a little prominence like a pug 

 nose. The chrysalis hangs in the same way as the 

 caterpillar, and remains in this state from nine to 

 fifteen days, according to the temperature. When 

 this period is terminated, the skin of the chrysalis 

 bursts open, and the butterfly issues from it, clings 

 to the empty shell till its cramped and drooping 

 wings have extended to their full dimensions, and 

 have become dried, upon which it flies away in pur- 

 suit of companions and food." 



Besides celery this caterpillar feeds upon parsley, 

 carrots, and related plants. The butterfly is known 

 to entomologists as Papillo asterias. 



