I2O 



HYMENOPTERA 



CHAP. 



relied on owing to the variation it presents both in this and the 

 allied sub-families. The Bembecides carry their prey to their 

 young tucked underneath their own bodies and hugged to the 

 breast ; they affect loose, sandy soils for nidification ; make use, 

 in the great majority of the cases where the habits are known, 

 of Diptera for provisions, and give these dead to the young ; 

 making repeated visits to supply fresh food to the progeny, which 

 notwithstanding this fact, are distributed in isolated burrows. 



One of the most interesting of Fabre's studies of the instincts 

 of Hymenoptera is devoted to Bembcx rostrata. The Bembecides 

 have the habit of forming their nests in the ground in wide 



expanses of sand, and of cover- 

 ing them up, they leave them 

 so that there appears to be 

 absolutely nothing by which 

 the exact position of the nest 

 can be traced ; nevertheless the 

 Bemliex flies direct to it with- 

 out any hesitation. How neces- 

 sary it is to these Insects to 

 possess this faculty of finding 

 their nests will be understood 

 when we recall that the Beinbex 

 does not provision its nest once and for all, but supplies the young 

 at first with only insufficient food, and has therefore to return at 

 daily, or other intervals, with a fresh store of provisions. The burrow 

 is made in the sand by means of the fore-legs ; these work with 

 such rapidity and skill that a constant stream of sand flows out 

 behind the Insect while it is engaged in the act of excavation. 

 The nest or cell in which the larva is to live, is formed by this 

 process of digging ; but no fastening together of the material 

 occurs, nor does any expedient seem to be resorted to, other 

 than that of making a way through the sand by clearing out all 

 the pieces of stick or stone that might diminish facility of access. 

 The cell being formed, the Bembex leaves the spot in search of 

 prey, and when it has secured a victim in the' shape of a two- 

 winged fly, it returns therewith to the burrow, and the booty is 

 placed therein, an egg being deposited on it. The wasp then 

 leaves the burrow, disguising, however, the spot where it is 

 situate, and flies away ; to proceed possibly with the formation 



FIG. 47. Bembex rostrata <$. Europe. 



