MY HOUSE AND GARDEN 29 



continued this till they had lowered the surface to the 

 depth of a little more than the eighth of an inch. This 

 much accomplished, they discontinued their labours. 

 They buried themselves in the centre of the circle, and 

 however long I might wait, they did not again appear. 



My experiments had shown me how the ant-lions 

 commenced their pits and the means by which they 

 rendered the surface outline so exactly circular ; but 

 I remained still in ignorance as to how the pits were 

 finished, and especially how the sides, down to the very 

 bottom, were made so smooth, so straight, and so 

 perfectly funnel-shaped. 



On other points also regarding the ant-lions my 

 curiosity to the last continued ungratified, and 

 especially on this, namely, how, living solely on ants 

 as they did, they managed to exist on the very small 

 number of ants they appeared to capture. 



I used to pass by the piece of ground where the ant- 

 lion pits were nearly every morning, and I used generally 

 to stop some little while to observe them. I never saw 

 any very large number of ants on the ground, and of 

 these I do not think one in twenty ever fell into the 

 pits. Either more fell in at other times of the day, or 

 else the ant-lions were able to subsist on an extra- 

 ordinarily small amount of food. 



Another thing also struck me as curious. The ant- 

 lions subsist upon ants, and yet when out of their pits 

 they never made any attempt to capture them. The 

 condition of things was, indeed, then reversed : the 

 ants were the assailants, the ant-lion the victim. 



The ant-lion is not at all a large insect. None that I 



