SOLITARY INSECTS. 185 



fly, is always placed in a downward direction. Its first in- 

 stinctive movements must, therefore, be in the same direction. 

 That the young flies may escape from their respective cells, 

 the mother digs a hole at the bottom of the long tube, which 

 makes a communication with the undermost cell and the open 

 air. Sometimes a similar passage is made near the middle of 

 the tube. By this contrivance, as all the flies instinctively 

 endeavor to cut their way downward, they find an easy and 

 convenient passage ; for they have only to pierce the floor of 

 their cells, which they readily perform with their teeth. 



Another small species of solitary bees dig holes in the earth 

 to make a convenient habitation for their young. Their nests 

 are composed of cylindrical cells, fixed to one another, and 

 each of them, in figure, resembles a thimble. Their bottom, 

 of course, is convex or rounded. The bottom of the second 

 is inserted into the entry of the first ; and the entry of the 

 second receives the bottom of the third. They are not all of 

 the same length. Some of them are five* lines long, others 

 only four, and their diameters seldom exceed two lines. 

 Sometimes only two of these cells are joined together; and, 

 at other times, we find three or four, which form a kind of 

 cylinder. This cylinder is composed of alternate bands of 

 two different colors; those of the narrowest, at the juncture 

 of two cells, are white, and those of the broadest are of a red- 

 dish brown. The cells consist of a number of fine mem- 

 branes, formed of a glutinous and transparent substance from 

 the animal's mouth. Each cell our bee fills with the farina of 

 flowers diluted with honey, and in this paste she deposits an 

 egg. She then covers the cell, by glding to its mouth a fine 

 cellular substance taken from the leaves of some plant ; and 

 in this manner she proceeds till her cylindrical nest is com- 

 pleted. The worms which are hatched from the eggs, feed 

 upon the paste, so carefully laid up for them by the mother, 

 till they are transformed into flies similar to their parents. 



Among wasps, as well as bees, there are solitary species, 

 which carry on no joint operations. These solitary wasps 

 are not less ingenious in constructing proper habitations for 

 their young, nor less provident in laying up for them a store 

 of nourishment sufficient to support them till they are trans- 

 formed into flies, or have become perfect animals. But to 

 give a detailed description of their operations, would lead us 

 into a prolixity, of which the plan of our work does not 

 admit. 



I shall now give soirce examples of the operations of asso- 

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