250 



HARDWICKE'S SCIENCE-GOSSIP. 



[Nov. 1, 1SG9. 



it was a male. One, two, three days elapsed ; my 

 poor male was half dead, the wings half broken, the 

 other cocoon was not giving any signs of an early 

 appearance ; imagine my anxiety ; it was a year lost. 

 The male died on the sixth day. The other moth 

 came out more than a fortnight after ; it was a male 

 also. During the summer of 1861, I found a dozen 

 worms, knowing then a little about their habits. In 

 the spring of 1862, I was fortunate enough to have 

 a pair of these insects that came out of the cocoon 

 at the proper time, and I obtained from their union 

 three hundred fecundated eggs. The pair which 

 gave me these eggs were the originators of the large 

 number which I have cultivated since. Of these 

 three hundred worms, I lost a great many, not 

 knowing their wants ; but I succeeded in obtaining 

 twenty cocoons in the autumn. It was only in 1865 

 that I became expert in cultivating them, and in 

 that year not less than a million could be seen 

 feeding in the open air upon bushes covered with a 

 net ; five acres of woodland were swarming with 

 caterpillar life. 



Fig. 220. Caterpillar of Telea Polyphemus. 



Early in summer, the chrysalis of Polyphemus | 

 which has been for eight or nine months imprisoned 

 in its cocoon, begins to awaken from its long torpor, 

 and signs of life are manifested by the rapid motion 

 of its abdomen. In the latitude of Boston, the 

 earliest date at which I have seen a perfect insect 

 is the 20th of May. Erom this time until the 

 middle of July, the moths continue to come out of 

 the cocoons. The cocoon being perfectly closed, 

 and a hard gummy, resinous substance uniting its 

 silken fibres firmly together, it is quite hard for the 

 insect to open it, as it has no teeth, nor instrument 

 of any kind to cut through it, and the hooked feet 

 are far too feeble to tear such a dense structure. 



But the moth must have some means of exit from 

 the cocoon. In fact they are provided with two 

 glands opening into the mouth, which secrete during 

 the last few days of the pupa state, a fluid which is 

 a dissolvent for the gum so firmly uniting the fibres 

 of the cocoon. This liquid is composed in great 



part of bombycic acid. When the insect has ac- 

 complished the work of transformation which is 

 going on under the pupa skin, it manifests a great 

 activity, and soon the chrysalis-covering bursts open 

 longitudinally upon the thorax ; the head and legs 

 are soon disengaged, and the acid fluid flows from 

 its mouth, wetting the inside of the cocoon. The 

 process of exclusion from the cocoon lasts for as 

 much as half an hour. The insect seems to be in- 

 stinctively aware that some time is required to 

 dissolve the gum, as it does not make any attempt 

 to open the fibres, and seems to wait with patience 

 this event. When the liquid has fully penetrated 

 the cocoon, the pupa contracts its body, and press- 

 ing the hinder end, which is furnished with little 

 hooks, agaiust the inside of the cocoon, forcibly 

 extends its body; at the same time the head pushes 

 hard upon the ^fibres, and a little swelling is observed 

 on the outside. The contractions and extensions of 

 the body are repeated many times, and more fluid 

 is added to soften the gum, until under these efforts 

 the cocoon swells, and finally the fibres separate, and 

 out comes the head of the moth. 

 In an instant the legs are thrust 

 out, and then the whole body ap- 

 pears ; not a fibre has been broken, 

 they have only been separated. 



To observe these phenomena, I 

 had cut open with a razor, a small 

 portion of a cocoon in which was 

 a living chrysalis nearly ready to 

 transform. The opening made was 

 covered with a piece of mica, of 

 the same shape as the aperture 

 and fixed to the cocoon with mas- 

 tic so as to make it solid and air- 

 tight ; through the transparent 

 mica, I could see the movements 

 of the chrysalis perfectly well. 

 When the insect is out of the cocoon, it imme- 

 diately seeks for a suitable place to attach its claws, 

 so that the wings may hang down, and by their own 

 weight aid the action of the fluids in developing and 

 unfolding the very short and small pad-like wings. 

 Every part of the insect on leaving the cocoon is 

 perfect, and with the form and size of maturity, ex- 

 cept the pad-like wings and swollen and elongated 

 abdomen, which still gives the insect a worm-like 

 appearance. The abdomen contains the fluids which 

 flow to the wings. 



When the still immature moth has found a suit- 

 able place, it remains quiet for a few minutes, and 

 then the wings are seen to grow very rapidly by the 

 afflux of the fluids from the abdomen. In about 

 twenty minutes the wings attain their full size, but 

 they are still like a piece of wet cloth, without con- 

 sistency and firmness, and as yet entirely unfit for 

 flight; but after one or two hours they become suffi- 

 ciently stiff, assuming the beautiful form character- 



