Packard.] 



INSECTS AS ARCHITECTS. 



307 



Maine I observed the female while engaged in making one 

 of these singular thimble-like rolls. "NV^hen about to deposit 

 an egg, she picks up a leaf with her mandibles, and begins 

 to cut with her jaws a slit near the base of the leaf on 

 each side of the midrib, and at light angles to it, so that the 

 leaf may be folded together. Before beginning to roll up 

 the leaf she gnaws the stem nearly off, so that after the roll 

 is made, and has dried for perhaps a day it is easily de- 

 tached by the wind and falls to the ground. Then folding 

 the leaf, she tightly rolls it up with her jaws and legs, neatly 

 tucking ill the ends, until a compact cylindrical solid mass 



Fig. 217. 



Fig. 



Cock's-comb gall. 



Attelabns. 



is formed. Before the roll is completed she deposits a single 

 egg, rarel}' two, in the middle, next to the midrib, where it 

 lies loose in a little cavity. While she is thus engaged, her 

 partner, a little smaller, may often be seen watching her 

 from the otlier end of the leaf, but never lending his aid, as 

 in the case of the timber beetles. The roll serves as a mass 

 of food for the young grub to feed upon, and may be i"e- 

 garded as an artificial bud. 



The larvfE of the Tiger beetles have the requisite instinct 

 to make deep tubular pits in which they lie in wait for their 



19 



