72 Journal New York Entomological Society. [Vol. xvi. 



stones rarely yield more than two beetles, but the mounds often con- 

 tain five or six at once, and with care will yield a crop every two or 

 three weeks. The beetles are found near the surface, none having 

 been taken below the plane of the base. As soon as it becomes warm, 

 from the middle of April onward, this species takes leave of the ants 

 and flies away ; like the Cicindelse it only flies during the hottest sun- 

 shine and for short distances, alighting suddenly on a stone or the 

 middle of a dusty road. Its flight is low and heavy, and after it lights 

 cannot take wing again without some delay, and I have seen it flying 

 as late as August. Whether after having left, the same beetles return 

 and breed among the ants, or whether it is a new brood that claims 

 their hospitality for the winter, is absolutely unknown. I never could 

 satisfy myself as to whether those found in the nests in June had re- 

 turned or were just preparing to leave." 



In 1 891 Lugger published a few observations on C. knochi Lee. 

 which he found at St. Anthony Park, Minnesota. He saw the beetles 

 mating during the early spring in an open field and being dragged 

 about by ants (species not mentioned). One individual "was found 

 sitting right over one of the small entrances of an ant nest. With 

 slow and very deliberate actions the beetle gradually enlarged the 

 hole under it, and in the course of nearly seven hours disappeared 

 from view." Lugger figures a peculiar cavity which was excavated in 

 the earth by five pairs of C. knochi kept in a jar. 



The observations above cited are all or nearly all that have been 

 published on the habits of Cremastochilus. In order to ascertain the 

 relations of these beetles to the ants I have on several occasions in- 

 stalled specimens of C. crinitus in artificial nests with F. gnava and 

 of C. canaliculatus and castanece with F. subsericea, schaufussi, nitidi- 

 ventris and integra. Beetles kept with the colonies in which they are 

 first taken, are treated with complete indifference by the ants. This 

 is sometimes the case also when the beetles are placed in a strange 

 colony of the same species of Formica, especially if this is F. schau- 

 fussi. More frequently a different picture, like that seen in the fol- 

 lowing experiment, is exhibited: April 19 I placed two C. castanece, 

 that had passed the winter with F. schaufussi, in a Fielde nest con- 

 taining several hundred workers and two deflated queens of F. integra. 

 The beetles at once " feigned death " and remained for several min- 

 utes lying on their backs, with retracted legs and antennae. They were 

 not noticed till they stretched out their appendages and began to walk 



