June, 1908.] Wheeler: Studies on Myrmecophiles. 75 



This is the more surprising because the colonies of schaufussi are very 

 small compared with those of subsericea, Integra, exsectoides, etc. * 



From the foregoing observations we may conclude that the Cre- 

 mastochili are not true guests, or symphiles, as Wasmann supposed 

 (1894), but persecuted intruders (synechthrans) that may eventually 

 become indifferently tolerated guests (synoeketes). This explains the 

 observations of previous writers. The three CremastocJtili which 

 Schwarz found arrested by the F. exsectoides workers were, in all 

 probability, individuals that had only just alighted on the mound, 

 whereas those taken in the galleries of the nest were old inhabitants. 

 The specimens with defective thoracic angles, described by Horn, had 

 probably been mutilated by the ants, as he suggests. Such mutila- 

 tions, however, would hardly be possible except in individuals that 

 had just escaped from their pupa-cases and were still soft. The view 

 here advocated is supported by the remarkable development of the 

 protective devises of the Cremastochili : their hard armor, the extra- 

 ordinary cup-shaped mentum which prevents the ants from getting at 

 the mouth-parts and the facility with which they can withdraw their 

 antennse into deep grooves on the sides of the head. 



But if this view is accepted, how are we to interpret the tufts of 

 yellow hairs, or trichomes on the thoracic angles, their obvious fasci- 

 nation for the ants and the peculiar oily red " myrmecophile color" 

 of some of the species ( C. saucius and spinifer) ? That the thoracic 

 angles represent adaptations to myrmecophily can hardly be doubted. 

 I have called attention to the remarkable manner in which these 

 structures, at least in some of the species, fit the mandibles of the 

 Formica workers. As the glands on these angles unquestionably emit 

 some odor which simultaneously attracts and irritates the ants, one 

 would be inclined to account for their development by supposing that 

 they tend to withdraw the hostile attentions of these insects from more 

 vulnerable organs. f But what are these organs? All parts of the 



* Mr. Davis calls my attention to the fact that Hamilton's statements in regard to 

 the flight of Cremastochilns are not strictly applicable to all the species. A consid- 

 erable number of C. harrisi were seen by Mr. Davis during the past April living 

 along the roads in the sandy pine barrens at Lakehurst, N. J. They were very agile 

 and difficult to catch, taking flight again after alighting with as much < 

 Cincindela:. 



f It is interesting to note that the European and North American species of an 

 allied genus of Cetoniine beetles, Osmoderma ( O. eremita L., eremicola Knoch and 

 scabra Beauv. ), have long been noted for their peculiar odors. Concerning our 



