XVIII A PARASITE— THE COCOON 249 



enters the gallery, clasping her prey. At that 

 instant, brief as it is, when the Bembex or any other 

 miner has half her body within the entrance, and is 

 about to disappear underground, the Miltogramma 

 arrives on the wing, perches on the prey slightly, 

 projecting beyond the hinder end of the Bembex, 

 and while she is delayed by the difficulties of enter- 

 ing, the Miltogramma, with unparalleled promptitude, 

 lays an egg on the prey, or two, or even three eggs, 

 successively. The hesitation of the Bembex, em- 

 barrassed by her load, lasts but the twinkling of an 

 eye ; but that matters not — it is long enough for the 

 fly to accomplish its misdeed without being dragged 

 beyond the threshold. What must not be the 

 suppleness of organs to achieve this instantaneous 

 laying of the egg ! The Bembex disappears, herself 

 introducing the enemy, and the Tachinid goes and 

 crouches in the sun, close to the burrow, and 

 meditates fresh crimes. If one would make sure 

 that the Dipteron's eggs have really been deposited 

 during this rapid manoeuvre, it suffices to open the 

 burrow and follow the Bembex to the bottom of her 

 abode. The prey which one takes from her bears 

 underneath at least one egg — sometimes more, 

 according to the length of the delay at the entrance. 

 These very minute eggs could only belong to a 

 parasite, and if any doubt remained, you can bring 

 up the brood in a box, and the result will be Diptera 

 larvae — later pupae, and finally Miltogramma. 



The fly shows wonderful sagacity in the moment 

 selected by it — the only one which could permit 

 of her carrying out her purpose with neither peril 

 nor vain efforts. The Bembex, half-way through 



