54 BEES AND WASPS [OH. 



seven combs; of these about 5000 had been used 

 thrice and over 6000 twice only. It is thus quite 

 probable that a large nest of ten or eleven combs 

 might in the course of the summer have a population 

 of some 50,000 or 60,000, and the vast majority of 

 these the offspring of the original "queen." 



Upon the outer wrappings of the nest there may 

 generally be found numbers of small oval white 

 specks. These are the eggs of a two-winged fly 

 (Pegomyia inanis). The parent fly walks unmolested 

 down the tunnel leading to the nest, and deposits her 

 eggs at random upon the "paper" of the envelopes. 

 When the maggots hatch out from these eggs they 

 immediately drop to the ground below the nest. In 

 the soil immediately under the entrance proper, which 

 is always at the bottom of the nest, there is a con- 

 siderable accumulation of organic matter. For the 

 wasps are scrupulously clean in their habits, and 

 always proceed to the entrance to void their excreta. 

 Here hanging on to the edge of the envelopes of the 

 nest they extend the abdomen vertically downwards 

 and discharge their evacuations upon the ground 

 below. It is in this miniature manure heap then 

 that the maggots of the fly find their food; and it 

 cannot be doubted that they play a useful part as 

 scavengers to the wasp community above. The 

 maggots of other flies may also be found within 

 the nest itself : Janet saw the maggots of Vohicella 



