ODYNERUS— AMMOPHILA. : 247 



downwards over its victims. Does one of them struggle ? 

 quick as liglitniog it retreats up the sheath out of 

 harm's way. 



In Odynerus the arrangement is very similar, but 

 the grub simply attaches itself to the support, and 

 does not construct a tube. Moreover, while in the 

 solitary bees and wasps the laying of the egg is generally 

 the final operation before the closing of the cell, in 

 Odynerus, on the contrary, or at least in OdyneruB 

 reniformis, the egg is laid before the food is provided. 

 This, perhaps, may have reference to the different con- 

 dition of the victims. 



According to Marchal,* Cerceris ornata practically 

 kills her victim ; moreover, she stings it not in, but 

 between, the ganglia, and though the first sting is 

 planted between the head and thorax, the following, 

 ones do not always follow the same order. 



At present the Ammophila supplies each cell with 

 one large caterpillar; but was this always so? One 

 species of Odynerus deposits in each cell no less than 

 twenty-four victims, another only eight. Eumenes 

 Amedei regulates the number according to the sex: 

 ten for the female grub, five only for the smaller mala 



Moreover, while phytophagous larvae will not gene-i 

 rally eat any plants but those to which they are 

 accustomed, it has been proved that, as a matter of 

 fact, these larvoD will feed and thrive on other insects 

 almost, if not quite, as well as on their natural food. 



Is it, then, impossible that in far bygone ages the 

 larvae may have grown more rapidly, so that the 

 victims had not time to decay; or that the ancestors 



* Marchal, " Sur I'lnstinct du Cerceris ornata,''* Arch. d. Zool. Ezper., 



1887. 



