222 INSECT LIFE 



XVI 



The nest is certainly there — underground, at the 

 depth of a few inches : in a little cell, dug in cool 

 firm sand, is an egg, perhaps a larva, which the 

 mother feeds daily with flies, the invariable food of 

 Bembex larvae. She must be able at any moment 

 to penetrate to this nest, carrying on the wing, 

 between her feet, the nursling's daily ration, just 

 as a bird of prey arrives at its eyrie carrying 

 game for its brood in its claw. But while the bird 

 returns to a nest on some inaccessible shelf of rock, 

 without any difficulty beyond the weight of its prey, 

 the Bembex must undertake each time the hard 

 work of mining, opening afresh a gallery blocked 

 and closed by ever-sliding sand in proportion as she 

 proceeds. The only stable part of this underground 

 abode is the spacious cell inhabited by the larva 

 amid the remains of a fortnight's feast ; the narrow 

 vestibule entered by the mother to go down to the 

 cell, or come forth for the chase, gives way each 

 time, at all events at the upper end, built in dry 

 sand, rendered even looser by her constant goings 

 and comings. Thus at each entrance or exit the 

 Hymcnopteron must clear out a passage. The exit 

 offers no difficulties, even should the sand have the 

 same consistency as when first stirred ; the insect's 

 movements are free ; it is safe under cover, can take 

 its time and use tarsi and mandibles at its leisure. 

 Going in is another matter. The Bembex is embar- 

 rassed by her prey, pressed to her body by her feet, 

 so that there is no free use of the mining tools. 

 What is more serious is that impudent parasites — 

 veritable bandits in ambush — are crouching here 

 and there about the burrow watching her difficult 



