The Life of the Fly 



The last two exceed the others in length and 

 stand out from the group in a double terminal 

 ploughshare. 



There is a round air-hole in front, on either 

 side of the thorax, and similar stigmata on the 

 flanks of each of the first seven abdominal 

 segments. When at rest, the nymph is curved 

 into a bow. When about to act, it suddenly 

 unbends and straightens itself. It measures 

 15 to 20 millimetres 1 long and 4 to 5 milli- 

 metres 2 across. 



Such is the strange perforating-machinethat 

 is to prepare an outlet for the feeble Anthrax 

 through the Mason-bee's cement. The struc- 

 tural details, so difficult to explain in words, 

 may be summed up as follows : in front, on the 

 forehead, a diadem of spikes, the ramming- 

 and digging-tool; behind, a many-bladed 

 ploughshare which fits into a socket and allows 

 the pupa to slacken suddenly in readiness for 

 an attack on the barrier which has to be de- 

 molished; on the back, four climbing-belts, or 

 graters, which keep the animal in position by 

 biting on the walls of the tunnel with their 

 hundreds of teeth; and, all over the body, 



1 -58 to .78 inch. — Translator's Note. 

 2 .i5 to .19 inch. — Translator's Note. 



58 



