
78 THE INSECT WORLD. 
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 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. These are not long able 
to resist the battering of the fly’s head, and the insect at length 
comes out triumphant. This fly, which should be blue, is then 
grey; it, however, comes quickly to perfection, at the end of 
three hours attaining its definite colour; and in a very short 
space of time every part of the animal becomes of that firmness 
and consistency which characterise it. At the same time, the 
wings, which at the moment it came into the world were only 
stumps, extend and unfold themselves by degrees. ‘The meat-fly 
is represented below (Fig. 55). 
One of the features in the formation of this fly which most 
attracted the attention of 

Y LP Réaumur, and which is likely 
\. ane , y to excite the curiosity of all 
= pe those who take an interest in 
if 8 i | insects, is the composition of 
f ANN yy A i ‘ its trunk. We will therefore, 
‘i lk | with that illustrious observer, 
f \ take a glimpse at the remark- 
‘Fig. 55.—Blue-bottle fly able and complicated appa- 
lec CU CE Ri sue ratus by the aid of which the 
fly can suck up liquids, and can even taste solid and crystalline 
substances, such as sugar. 
It is no difficult matter to make a fly show its trunk, 
extended to its full extent. One has only to press between 
the finger and thumb either the two sides or the upper and under 
part of the thorax. It is thus forced at once to put out its 
tongue. 
The tongue appears to be composed of two parts joined together, 
