CHEESE MAGGOTS. 



265 



maintain its balance. It then bends itself into a 

 circle, catches the skin near its tail with its hooked 

 mandibles, and after strongly contracting itself from 

 a circular into an oblong form, it throws itself with a 

 jerk into a straight line, and thus makes the leap. 



Cheese hoppers (PiophUa casei, Fallen), a, the maggot ex- 

 tended ; , in a leaping position ; rf, the same magnified ; e, the 

 fly magnified ; y, g-, the fly, natural size. / 



One very surprising provision is remarkable in 

 the breathing-tubes of the cheese maggot, which are 

 not placed, as in caterpillars, along the sides, but a 

 pair near the head and another pair near the tail. 

 Now, when burrowing in the moist cheese, these 

 would be apt to be obstructed; but to prevent this, 

 it has the power of bringing over the front pair a 

 fold of the skin, breathing in the meanwhile through' 

 the under pair. Well may Swammerdam denomi- 

 nate these contrivances ' surprising miracles of God's 

 power and wisdom in this abject creature.' 



Like the other destructive insects above mentioned, 

 the multiplication of the cheese fly is checked by some 

 insect, whose history, so far as we are aware, is not 

 yet known. Swammerdam found many of the maggots 

 with other larvae in their bodies; but he did not trace 

 their transformations. If they were the larvae of an 

 ichneumon, it must be exceedingly minute. 



It must have attracted the attention of the most 

 VOL. vi. 23 



