BEHAVIOR OF THE ANT-LION. 279 



soil of Missouri and Kansas; some were found in cinders in shel- 

 tered places along railroad tracks; some, in disintegrated mortar 

 along the walls of buildings; some, in the rotton-wood dust of 

 hollow logs; none of these was obtained from sand. In the wide 

 jelly glasses of my insectary, where each larva was kept in solitary 

 confinement, some were placed in loamy clay, some in sifted coal 

 ashes, some in coal ashes that had been weathered for a year, 

 some in fine sand and others in coarse. The larvae seemed to 

 flourish as well in one medium as in the other. 



The ant-lion usually begins the construction of its pit by striking 

 out a circle in the friable earth. Using its abdomen as a plow- 

 share and its head as a shovel, the larva burrows backward, in a 

 circular path, just beneath the surface of the soil, tossing upward 

 and outward the dirt that falls upon its head. Almost all of 

 the articles that I have read state that this initial circle marks 

 the outer boundary of the finished pit. With the American 

 ant-lion of the Middle West this is not always so. In most 

 cases observed by me the finished pit is wider than the diameter 

 of this circle. In the first place, the falling inward of the soil 

 as the excavation progresses enlarges the diameter. Then, too, 

 the ant-lion sometimes enlarges the partly or apparently entirely 

 completed pit. After this first circle is completed, within this 

 the ant constructs, in a similar manner, a deeper adjacent circle 

 and so on until the center is reached. Then, with the major 

 portion of its body hidden in the walls of the pit and using its 

 head and mandibles as a shovel, it tosses out the material from 

 the bottom of the pit, until the dirt no longer runs down the 

 sides. 



European writers state that the ant-lion shovels sand on to its 

 head by means of one of its forefeet, and Kirby and Spence (8) 

 insist that, in excavating its burrow, the ant-lion reverses the 

 direction it is going at the completion of each circle, so as to alter- 

 nately exercise each foreleg. In our American ant-lion this 

 pair of forelegs functions, not as a scrape, but as a brace to the 

 body when the ant-lion is shovelling dirt or turning. Patient 

 watching with a magnifying glass has failed to detect the fore- 

 foot loading dirt upon the head; and certainly the ant-lion does 

 not reverse the direction it is going every time it completes a 



