18 



fish,* with other amphibious shellfish, and some insects, build houses 

 along the margins of water courses, where the soil is too wet and 

 cold, and rear them above tide water. They resemble small chim- 

 nies, and are so firmly cemented that water will not penetrate their 

 walls. The glutinous secretion they employ resembles the slime on 

 the bodies of snails, which seems to be used for the same purpose. 



When the locust takes its final leave of its cell, it selects the still- 

 est and most private hour, about day-break, to guard against the 

 accidents to which it is liable in so weak and defenceless a state, 

 till it can fly. Some cannot divest themselves of their sloughs 

 under a cold damp atmosphere. Others ascend at so great a dis- 

 tance from any object by which they can climb up, that they perish 

 before they can get the benefit of the sun. Great numbers are 

 devoured by hogs, squirrels, all kinds of poultry and birds, which 

 live and fatten on them. 



No sooner has the pupa issued from the earth than we perceive 

 a change which leads almost immediately to the divestment of its 

 coat. It becomes browner and harder, more particularly on the 

 back, between the head and wings. The latter are still more de- 

 veloped, but wear a delicate, silk-like appearance. The wings 

 become amber, and the wing bones assume a bright orange colour. 



The process by which they extricate themselves from the slough 

 is slow at first, though soon finished. It is similar to the shedding 

 of a crab, except the part through which the body is drawn from 

 the shell. That of the crab open laterally at the side, opposite 

 the eyes and mouth the locust longitudinally, in the middle of the 

 back. They are both disengaged by the muscles of their legs, 

 with their claws constantly in motion till the process is finished. 



We saw the first that had sloughed on the eighteenth of May, a 

 few on the nineteenth, and from that time they multiplied almost 

 incalculably, till the twenty fifth. From that day till the twenty 

 third of June the numbers declined in the same ratio. On the 

 fourth of July we found very few, and on the fifth one. 



We found the first pair in sexual union on the twenty fjth of May, 



* Cancer Astacus. 



