240 On two Species of I he Sphex or IVasp, 



The fifth contained an envelop in which was a large 



worm not yet in the state of a chrysalis; the whole Grains. 



weighed - - - - 34- 



The sixth and seventh cellules were empty j the young 

 wasp had abandoned them. , 



This examination proves that the wasp distributes with 

 much judgment the quantity of food necessary for its pro- 

 geny ; in most of the cellules, for instance, I ought to have 

 found twenty-two or twenty-three spiders, and yet some- 

 times there are only five or six, but in this case they are 

 very large ones. It appears also, that when the worm has 

 attained its greatest size, its weight is only one half of that 

 of the food it has consumed. 



If it should become necessary to break through the bar- 

 rier antiently traced between reason and instinct, the oeco- 

 nomy of the whole class of hymenopteree, and particularly 

 of the wasps, may contribute to it. I shall relate a singular 

 example which appears to be above mere instinct. 



For the purpose of inspecting one of these insects (the 

 Pennsylvanian wasp) while at work, I was obliged to remove 

 a small distance from the wall a picture behind which the 

 nest was placed. In doing so I deranged several cellules, 

 because the earthy mastic which joined them to the wall 

 was broken in several places and exposed the spiders and 

 the young worms to view. 



I held the frame about an inch from the wall in order to 

 see what passed behind. In a short time the wasp arrived, 

 loaded with a round lump of clay. It came merely for the 

 purpose of making a new cellule ; but seeing that its former 

 works were deranged, it began to run rapidly over the cel- 

 lules, apparently hesitating what to do. At last it depo- 

 sited the clay upon the edge of one of the apertures, and 

 began to spread it with its snout, pushing it before it, in, 

 the attitude of a sow digging in the ground. It emitted a 

 shrill buzzing w hen at work. After having very properly 

 rcplastercd the work, it flew away. In four minutes it re- 

 turned with a new load of clay, which it deposited in the 

 next aperture. It repeated its visits four times ; and after 

 having finished the repairs and being convinced of the 

 1 goodness 



