HABITATIONS OF INSECTS. 301 



by the Grylli, Cicindelce, and a few others, are the only ones properly 

 belonging to it. 



The habitation of one of these (^Cteniza Cfementaria) is subterraneous ; 

 not a mere shallow cavity, but a tube or gallery upwards of two feet in 

 length, and half an inch broad. This tunnel, so vast compared with the 

 size of the insect, it digs by means of its strong jaws in a steep bank of 

 bare clay, so that the rain may readily run off without penetrating to its 

 dwelling. Its next operation is to line the whole from top to bottom with 

 a web of fine silk, which serves the double purpose of preventing the 

 earth that composes the walls from falling in, and, by its connection with 

 the door of the orifice, of giving information to the spider of what is pass- 

 ing above. You doubtless suppose that in saying door, I am speaking 

 metaphorically. It could never enter into your conception that any 

 animal, much less an insect, could construct any thing really deserving of 

 that name — any thing like our doors, turning upon a hinge, and accurately 

 fitted to the frame of the opening which it is intended to close. Yet 

 such a door, incredible as it may seem, is actually framed by this spider. 

 It does not, indeed, like us, compose it of wood, but of several coats of 

 dried earth fastened to each other with silk. When finished, its outline is 

 as perfectly circular as if traced with compasses ; the inferior surface is 

 convex and smooth, the superior flat and rough, and so like the adjoining 

 earth as not to be distinguishable from it. This door the ingenious artist 

 fixes to the entrance of her gallery by a hinge of silk, which plays with 

 the greatest freedom, and allows it to be opened and shut with ease ; and, 

 as if acquainted with the laws of gravity, she invariably fixes the hinge at 

 the highest side of the opening, so that the door when pushed up shuts 

 again by its own weight. She has not less sagaciously left a little edge 

 or groove just within the entrance, upon which the door closes, and to 

 which it fits with such precision thut it seems to make but one surface 

 with it. Such is the astonishing structure of this little animal's abode ; 

 nor is its defence of its subterraneous cavern less surprising. If an 

 observer adroitly insinuates the point of a pin under the edge of the door, 

 and elevates it a little, he immediately perceives a very strong resistance. 

 What is its cause ? The spider, warned by the vibrations of the threads 

 which extend from the door to the bottom of her gallery, runs with all 

 speed to the door, fastens its legs to it on one side, and on the other to 

 the walls, and, turning upon its back, pulls with all its might. Thus the 

 door is alternately shut or opened, as the exertions of the observer or of 

 the spider prevail. It is easy to guess which will in the end conquer ; 

 and the spider, when it finds all resistance ineffectual, betakes itself to 

 flight, and retreats. If, to make a further experiment, the observer fastens 

 down the door so that it cannot be forced open, the next morning he will 

 find a new entrance, with a new door formed at a small distance ; or, if 

 he take the door entirely away, another will be constmcted in less than 

 twelve hours. 



The habitation thus singularly formed and defended is not at all used as 

 a snare, but merely as a safe abode for the spider, which hunts its prey at 

 night only ; and, when caught, devours it in security at the bottom of its 

 den, which is generally strewed with the remains of coleopterous insects.^ 



* Sauvages Hist, de I' Acad, dgs Sc. de Paris, 1758, p. 26. 



26 



