2g INSECT ARCHITECTURE. 



accident, she immediately sought for at the bottom of 

 the wall, and carried off like the rest. It was no easy 

 matter to get out one of the fragments, as may readily 

 be conceived, when the size qf the insect is compared 

 with that of the entrance, of which this ({£) is the 

 exact size, as taken from the impression of a hit of 

 dough upon the hole when finished. It was only by 

 seizing the fragment with her jaws, and retreating 

 backwards, that the matter could be accomplished; 

 though, after the interior of the excavation was barely 

 large°enough to admit of her turning round, she more 

 than once attempted to make her exit head- foremost, 

 but always unsuccessfully. The weight of the frag- 

 ments removed did not appear to impede her flight, 

 and she generally returned to her task in about two 

 or three minutes 



Within two days the excavation was completed; 

 but it required two other days to line it with a coating 

 of clay, to deposit the eggs, two in number, and, no 

 doubt, to imprison a few live spiders or caterpillars, 

 for the young when hatched,— a process which was 

 first observed by Hay and Willughby*, but which 

 has since been frequently ascertained. In the present 

 instance, this peculiarity was not seen ; but the little 

 architect was detected in closing up the entrance, 

 which was formed of a layer of clay more than 

 double the thickness of the interior lining. In No- 

 vember following, we hewed away the brick around 

 this nest, and found the whole excavation was rather 

 less than an inch in depth. 



Notwithstanding all the precautions of the careful 

 parent to conceal her nest, it was found out by one of 

 the cuckoo-flies (Tachina larvarum?)— probably a 

 common species very similar to the house-fly, but 



* Bay, Hist. Insect. 254. 



