170 NATURE'S TEACHINGS. 



almost like horse-pistols suspended by the butt, so round is the 

 nest, and so long and narrow is the tunnel-like entrance. 



PASSING to the insect world, we find the same principle 

 carried out by the now familiar Mason- wasp (Odynerm mura- 

 rius), some of whose nests are represented in the illustration. 



This insect makes a burrow, and at the bottom of it deposits 

 an egg, together with a number of little caterpillars on which 

 the grub, when hatched, will feed. The mother Wasp is not 

 allowed to pursue this task without taking precautions against 

 the admission of enemies to her burrow, especially the ichneu- 

 mon-flies. As may be inferred from its popular name, the 

 Sand -wasp always selects a sandy spot for its burrow, and 

 generally chooses a piece of tolerably hard sandstone, which it 

 is able to bite into little pellets, aided by a kind of liquid which 

 it secretes. 



The following account of the manner in which the Mason- 

 wasp forms and defends its home is taken from the invaluable 

 "Insect Architecture," by Rennie. 



The author begins by describing the form and depth of the 

 burrow, and the soil in which it is made. He then proceeds to 

 show the wonderful manner in which the mother Wasp purveys 

 food for the use of her future young whom she will never see. 

 Guided by instinct, she places in the burrow exactly the 

 number of caterpillars which the young Mason-wasp will have 

 to consume before it attains its perfect condition. It is believed 

 that she partially paralyzes them with her sting before 

 placing them in the burrow. At all events, when they are 

 once packed away, they never move, so that the tiny Wasp grub 

 can feed upon them quite at its leisure. 



Here is Rennie's account of the Sand-wasp and her burrow- 

 making : 



" When this wasp has detached a few grains of the moistened 

 sand, it kneads them together into a pellet about the size of 

 one of the seeds of a gooseberry. 



" With the first pellet which it detaches, it lays the founda- 

 tion of a round tower, as an outwork, immediately over the 

 mouth of its nest. Every pellet which it afterwards carries off 

 from the interior is added to the wall of this outer round tower, 

 which advances in height as the hole in the sand increases in 



