198 



INSECT ARCHrTECTURE. 



of the oak, near an offgoing of the branchlets whose 

 angle may afford it some protection. It then measures 

 out, with its body for a rule, the space destined for 

 its structure, the basement of which is of a triangular 

 form, with the apex at the lower end. The building 

 itself is composed of small rectangular strap-shaped 

 pieces of the outer bark of the branch cut out from 

 the immediate vicinity; the insect indeed never tra- 

 vels farther for materials than the length of its own 

 body. Upon the two longest sides of the triangular 

 base it builds uniform walls, also of a triangular 

 shape, and both gradually diverging from each other 

 as they increase in height. These are formed with 

 so much mathematical precision, that they fit exactly 

 when they are afterwards brought into contact. As 

 soon as the little architect has completed these walls, 

 which resemble very much the feathers of an arrow, 



Magnified Cells ofPyralis Strigidalis? 



a The walls before they are joined. &. Walls joined, but not 

 closed as top. c. Side view of structure complete. 



