28 INSECT ARCHITECTURE. 



accident, she immediately sought for at the bottom of 

 the wall, and carried ofFliliethe rest. It was no easy 

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

 be conceived when the size of the insect is compared 

 with that of the entrance, of Avhich this (U) is the 

 exact size, as taken from the impression of a bit 

 of dough upon the hole when finished. It was 

 only by seizing the fragment with her jaws, ^nd re- 

 treating backwards, that the matter could be accom- 

 plished ; 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 fragments removed did not appear to 

 impede her flight, aiid she generally returned to her 

 task m 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 {ew live spiders or caterpillars, 

 for the young when hatched, — a process which was 

 first observed by Ray and Willoughby*, 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 jVo- 

 vember following; we liewed 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 {Tuchina larvurum}) — probably a 

 common species very similar to the house-fly, but 



* Ray, Hist. Insect. 254. 



