44 OUT OF DOORS. 



account of their small size and powers of jumping) are 

 used for this purpose. How the little sand-wasp grub 

 manages to eat them is more than I know, but perhaps 

 the hard integuments may be softened by the damp of 

 the burrow. This, however, is merely conjecture. 



There is yet one insect to be accounted for. I have 

 already mentioned the ruby-tail flies that in July were 

 flitting so anxiously over the face of the quarry, their 

 burnished crimson and blue mail flashing in the sun- 

 beams like living jewellery. They were on a somewhat 

 similar errand to that of the bees and wasps, but they 

 carry it out in a different manner. They are parasites 

 on the sand- wasps, and just as the sand- wasp grub eats 

 the flies, so the larva of the ruby-tail eats both the 

 sand-wasp grub and all its store of food. From ob- 

 servations that have been made on the habits of these 

 insects, the larva seems at first to suck, rather than to 

 eat, the unfortunate grub on which it feeds; but, 

 having extracted nearly all the juices, proceeds to de- 

 vour the other portions of the body. 



The mother ruby-tail is wonderfully persevering in 

 her attempts to insert an egg into some other insect's 

 nest. Sometimes the rightful owner detects the in- 

 truder, and then the latter generally suffers for her 

 deeds. When attacked by her angered foe, she usually 

 tries to shield herself by rolling her body into a ball 

 and lying motionless. Even this ruse, however, does 

 not always save her, and she loses her life, together with 

 her hope of providing for a future generation. 



