78 THE INSECT WORLD. 



all motion, and cannot any longer either lengthen or shorten, or 

 dilate or contract itself. Life seems to have left it. " It would be 

 considered a miracle," says Reaumur, "if we were told there was 

 any kind of quadruped of the size of a bear, or of an ox, which at a 

 certain time of the year, the beginning of winter for instance, dis- 

 engages itself completely from its skin, of which it makes a box of 

 an oval form ; that it shuts itself up in this box ; that it knows 

 how to close it in every part, and besides that it knows how to 

 strengthen it in such a manner as to preserve itself from the effects of 

 the air and the attacks of other animals. This prodigy is presented 

 to us, on a small scale, in the metamorphosis of our larva. It casts 

 its skin to make itself a strong and well-closed dwelling." 



If one opens these cocoons only twenty-four hours after the 

 metamorphoses of the worms, no vestige of those parts appertaining 

 to a pupa is to be found. But four or five days afterwards, the 

 cocoon is occupied by a white pupa, provided with all the parts of a 

 fly. The legs and wings, although enclosed in sheaths, are very 

 distinct ; these sheaths being so thin that they do not conceal them. 

 The trunk of the fly rests on the thorax ; one can discern its lips, and 

 the case which encloses the lancet. The head is large and well 

 formed, its large, compound eyes being very distinct. The wings 

 appear still unformed, because they are folded, and, as it were, 

 packed up. It is a fly, but an immovable and inanimate fly ; it is 

 like a mummy enveloped in its cloths. 



Nevertheless, it is intended this mummy should awake, and when 

 the time comes it will be strong and vigorous. Indeed, it has need 

 of strength and vigour to accomplish the important work of its life. 

 Although its coverings are thin, it is a considerable work for the 

 insect to emerge, for each of its exterior parts is enclosed in them as 

 in a case, much the same as a glove fits tightly to all the fingers of 

 the hand. But that for which the most strength is necessary is the 

 operation of forming the opening of the cocoon, in which as a 

 mummy it is so tightly enclosed. 



The fly always comes out at the same end of the cocoon, that is, 

 at the end where its head is placed, and also where the head of the 

 larva previously was. This end is composed of two parts of two 

 half cups placed one against the other. These can be detached from 

 each other and from the rest of the cocoon. It is sufficient for the 

 fly that one can be detached, and in order to effect this, it employs 

 a most astonishing means. It expands and contracts its head 

 alternately, as if by dilatation ; and thus pushes the two half cups 

 away from the end of the cocoon. This is not long able to resist the 



