1 8o OUR INSECT FRIENDS AND FOES 



in which the larva lies. Presently the Bembex 

 drops to within a few inches of the ground, 

 instantly the flies rise and take up their posi- 

 tion in a line behind her, awaiting the moment 

 when she will enter her burrow. Sometimes 

 the Bembex will manoeuvre about over the 

 ground trying to shake these troublesome pests 

 off, but with quiet persistence they follow her 

 every movement, always keeping exactly the 

 same distance from her. Sometimes the perse- 

 cuted insect rises and flies off again with her 

 prey, then the flies drop to the ground, take up 

 their former positions, and patiently await her 

 return. At length, her patience exhausted, the 

 Bembex makes a sudden dart for her burrow. 

 The moment she pushes her head into the sand 

 the flies close in upon her, and with lightning 

 rapidity, those that are nearest, deposit their 

 eggs upon the prey that the Bembex is carrying 

 down to her larva. 



In this way the Bembex herself introduces 

 the eggs of the parasites into her burrow, and 

 sometimes as many as ten dipterous larvae have 

 been found in a cell in company with its lawful 

 owner. Strangely enough the Bembex never 

 attempts to destroy or eject the intruders, 

 but philosophically accepting the burden forced 

 upon her, tries to feed all the larvae she finds in 

 her nest regardless of their parentage. In the 

 end, as it is quite impossible for the Bembex to 

 bring enough food to satisfy so many hungry 

 mouths, her own larva perishes for lack of 

 sufficient nourishment, or it sometimes hap- 

 pens, if the supply of food is very short, that 



