APHIDIVOEOUS CRABRONID^. 159 



It is probable that a like habit of numbing their vic- 

 tims is practised by the Aphidivorous Crabronidas ; 

 but, as many days must elapse between the hatching of 

 the young Crabro and its metamorphosis into the pupa, 

 there is room for some surprise that the stored Aphides 

 during such a protracted period should continue in a 

 state fresh and fit for food. Possibly a torpid condi- 

 tion, something analogous to hybernation, may be in- 

 duced by the action of the sting-poison, whereby the 

 vital functions are placed in abeyance, or reduced to 

 their minimum state of activity. Certain it is that 

 Aphides and other insects may be artificially preserved 

 alive for weeks deprived of food, if care be taken to 

 check evaporation from their bodies, by keeping them 

 in a damp atmosphere. 



Such a humid state obtains within the pith of briars, 

 or the raspings of rotten wood, and as the nursiug cells 

 of these Hymenoptera are commonly constructed in 

 such situations, the conditions are eminently favorable 

 for producing a protracted sleep. 



It would appear that each species of the fossorial 

 Hymenoptera confines itself, as a rule, to a particular 

 prey, and indeed to a particular species of prey. The 

 number of individuals introduced into a burrow much 

 depends on the size of the insect to be fed. In some 

 cases, where lepidopterous larvae are used, but one 

 specimen suffices for the food of the young ; but in 

 other cases as many as sixty or even one hundred 

 individuals may be huddled together in a single cell. 

 Thus it is that Grahro vagus crams its cells with blue- 

 bottle-flieSj on which the w^hite fleshy apodous grub 

 feeds. 



These larvas are usually enclosed in thin paper-like 

 cases, the remains of which may be often seen in such 



gean's words are interesting : " Recourbaut son abdomen la pevce 

 (I'arachnide) dn fatal aignillon, qui lance dans la plaie la liqueiu-e 

 venemeuse qui occasionne sur le champ la paralyse de la victime sans 

 lui oter la vie. Celle ci conservee, sans etre autvemeut blessee montrait 

 encore au bout de trois semaines de legers signes de vie par le niouve- 

 ment des pattes et la souplesse des articulations," &c. &c. 



