﻿58' Journal New York Ent. Soc. lvol. in. 



pressions of leaves (Fig. 4) ; proving that the fine clay or forest 

 mould, worked with a cement exuded by the insect, was quite 

 plastic. It would seem that the thin claws of the pupa were too 

 inadequate for carrying very soft material. It may be that the 

 little miner and mason is his own hod-carrier; conveying his load 

 of plaster to the walls of his building on his head : a conjecture 

 that would seem fanciful indeed were it not for the fact that the 

 intelligent creature when burrowing downward, does what amounts 

 to practically the same thing. Having displaced a pellet he clev- 

 erly places it on his head, and by a turn of his body carries the 

 pellet to the earth above and presses it in. 



From personal observations I am inclined to think that the 

 structures are built at night ; the builders beginning work at twi- 

 light, for the same' reason that they choose that time to emerge 

 from their burrows to moult ; as the absence of the sun's heat in 

 one case would prevent the exuding cement from drying, and 

 keep the rim of the dome moist for cohesion ; in the other the 

 wings would not dry too rapidly for full expansion. Hoping that 

 I might see the pupa^ at work I broke off the tops of several domes, 

 but after long watching observed no attempt at repairs. All but 

 two or three were finally roofed over, but on the inside, consider- 

 ably below the rim (Fig, 5) ; probably on account of being damper 

 there, or that the pup^ could more readily prepare the inner wall 

 for the masonry by smearing it with the adhesive cement. Among 

 the multitude of domes a few were found that had been left un- 

 finished. Doubtless the builders had been captured by crows, or 

 other foragers. They afford an interesting illustration of the 

 manner of placing the pellets on the rim. (Fig. 6.) 



The scope of this article is confined to a record of observations 

 and analyses of salient facts. Much that might be considered of 

 interest to entomologists must remain unwritten for want of space. 

 But I trust some light has been thrown on what has been con- 

 sidered one of most m.arvelous of the phenomena connected with 

 insect life. If the explanation offered is the true one, it would 

 seem to render still more diaphanous the supposititious veil between 

 "instinct" and reason, and emphasize our impressions of the long 

 pathway that has been trodden by our little friends and prede- 

 cessors. 



