252 HABITATIONS OF INSECTS. 



in a direction perpendicular to her body. Thus, without rule or compasses 

 do these diminutive creatures mete out the materials of their work into 

 portions of an ellipse, into ovals or circles, accurately accommodating the 

 dimensions of the several pieces of each figure to each other. What other 

 architect could carry impressed upon the tablet of his memory the entire 

 idea of the edifice which he has to erect, and, destitute of square or plumb- 

 line, cut out his materials in their exact dimensions without making a 

 single mistake ? Yet this is what our little bee invariably does. So far 

 are human art and reason excelled by the teaching of the Almighty. 1 



Other insects besides bees construct habitations of different kinds for 

 their young, as various species of burrowing wasps (Fossores), Geotrupes, 

 &c., which deposit their eggs in cylindrical excavations that become the 

 abode of the future larvae. In the procedures of most of these, nothing 

 worth particularising occurs ; but one species, called by Reaumur the 

 mason-wasp (Odynerus murarius), referred to in a former letter, works 

 upon so singular a plan, that it would be improper to pass it over in silence, 

 especially as these nests may be found in this country in most sandy banks 

 exposed to the sun. This insect bores a cylindrical cavity from two to 

 three inches deep, in hard sand which its mandibles alone would be 

 scarcely capable of penetrating, were it not provided with a slightly gluti- 

 nous liquor which it pours out of its mouth, that, like the vinegar with 

 which Hannibal softened the Alps, acts upon the cement of the sand, and 

 renders the separation of the grains easy to the double pickaxe with which 

 our little pioneer is furnished. But the most remarkable circumstance is 

 the mode in which it disposes of the excavated materials. Instead of throw- 

 ing them at random on a heap, it carefully forms them into little oblong 

 pellets, and arranges them round the entrance of the hole so as to form a 

 tunnel, which, when the excavation is completed, is often not less than 

 two or three inches in length. For the greater part of its height this tun- 

 nel is upright, but towards the top it bends into a curve, always, however, 

 retaining its cylindrical form. The little masses are so attached to each 

 other in this cylinder as to leave numerous vacuities between them, which 

 give it the appearance of filagree-work. You will readily divine that the 

 excavated hole is intended for the reception of an egg, but for what pur- 

 pose the external tunnel is meant is not so apparent. One use, and perhaps 

 the most important, would seem to be to prevent the incursions of the 

 artful Ichneumons, Chrysidcs, &c., which are ever on the watch to insinuate 

 their parasitic young into the nests of other insects : it may render their 

 access to the nest more difficult ; they may dread to enter into so long 

 and dark a defile. I have seen, however, more than once a Chrysis come 

 out of these tunnels. That its use is only temporary is plain from the 

 circumstance that the insect employs the whole fabric, when its egg is laid 

 and store of food procured, in filling up the remaining vacuity of the hole ; 

 taking down the pellets, which are very conveniently at hand, and placing 

 them in it until the entrance is filled. 2 Latreille informs us that a nearly 

 similar tunnel, but composed of grains of earth, is built at the entrance of 

 its cell by a bee of his family of pioneers? 



The habitations hitherto described are used simply as an abode for the 

 future larva springing from the egg deposited in them by the parent female, 

 and as a storehouse for its food; but in another class of insect habitations 



i Reaum. vi. 971 24. Hon. Ap. Angl i. 157. Apis. **. c. 2. . 



3 Reaun. vi. 251 257. t. xxvi. f. 1. 5 Latr. Fourmis, 419. 



