26 BEES AND WASPS [OH. 



happens to alight close by. All these resemblances 

 to a fly appear to have a purpose. 0. unigliimis 

 provisions her nest with flies, and thanks to her 

 disguise is able to pass and even play among the flies 

 without arousing suspicion. She affords us one of 

 the very few examples of what is termed "aggressive 

 mimicry." Her main object in life is to secure as 

 many flies as possible with the minimum of trouble. 

 Her burrow is about three inches deep, and is always 

 placed close by or even in a patch of bare soil where 

 flies may bask; but she disdains the "sitting" shot, 

 and invariably catches her prey in mid air, swooping 

 on it like some tiny falcon. On leaving her burrow 

 she covers the entrance by a few quick scratches at 

 the sand and mounts up into the air to join in the 

 throng of flies whose buzz overhead may be heard 

 on nearly any hot, fine day. No time is wasted ; in a 

 few seconds she falls again to earth grasping a strug- 

 gling fly in her strong legs: the quietus is quickly 

 administered by the sting and the paralysed body 

 dragged down the burrow. Six times in five minutes 

 have I seen the same individual insect-hawk success- 

 fully repeat the whole of the above tragedy; and 

 when the completed burrow was opened up there lay 

 sixteen helpless flies intended as food for the grub 

 which should have emerged from the single egg 

 placed among them. 



This little wasp has a very peculiar method of 



