xxii President' 's Address. [Aug- 28, 



and smooth them with your jaws so as to resemble the surface of the 

 old wall ; all these precautions are now in vain, instead of an 

 Odynerus, a Chrysis, the metamorphosis of which is shorter, will issue 

 from it. 



I shall later on revert to that Odynerus. 



A Sphex, a Scolia, a Pompilus, or an Odynerus provides living 

 insects for the sustenance of its progeny. The choice varies much : 

 caterpillars, grasshoppers, flies or beetles, but spiders predominate. 

 With these they store their nest or gallery, and the minute grub 

 issuing from the egg is able to devour the large piece provided for its 

 use before reaching its pupal stage, which is never of very long 

 duration, the transformation from the pupa to the perfect state always . 

 taking much more time than the first metamorphosis. 



That grub is very small, very fragile ; a single contortion of the 

 prey provided by the motherly instinct will reduce it to pulp ; the 

 powerful jaws of the Orthopteron, the Coleopteron, or the spider are - 

 not less to be dreaded than the kick of legs bristling with spines. 

 Were it shaken off by the victim that is to be, its legless condition, its 

 unprotected covering, militate against all possibility of crawling back 

 to its prey, of fastening again its mandibles on the succulent morsel, . 

 hence starvation and its correlative — extinction of the species. 



Why does the mother select for its future progeny such a redoubt- 

 able host ? Because before the cell is stored with a living prey that 

 prey has been paralysed. 



I take a Sphex. Armed with powerful jaws, having legs eminently 

 adapted to fossorial purposes, and with an abdomen articulated on a 

 long peduncle and provided with a powerful sting, this insect is really 

 a formidable foe, one that is eminently adapted to tearing its prey and 

 making mincemeat of it ; but, unlike some Vespidae, it feeds on the 

 pollen of flowers. 



Yet the whole of the energy it is capable of will be expended on 

 providing for its progeny, in ensuring it such a store of food as will last 

 until it is able to spin its own cocoon and undergo its metamorphosis. . 

 One condition, however, is essential. The food must be always fresh ; : 

 if dried up or beginning to decompose, the grub will not touch it, will 

 rather die of starvation. It follows apparently that if the larva is to 

 be fed on living organism, it must needs be supplied regulary, daily, 

 nay hourly. But the Sphex does not proceed thus. It stores the 

 cell, lays its egg, and closes the door — the same to be opened by its 

 progeny when it reaches the adult stage. 



I am going to tell you now the process used for obtaining that 

 result, and I consider it one of the most marvellous cases of adaptation 

 to a purpose displayed in the whole of the insect world. 



I am in the Hex River Valley. I have captured several Harpactopus 



