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 sev^en 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^ long and 4 to 5 milli- 

 metres^ 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, 



^.58 to .78 inch. — Translator's Note. 

 2.15 to .19 inch. — Translator's \ot^. 



58 



