136 Journal New York Entomological Society. [Vol xvi. 



European H. ferrugineus, are unknown. We may, therefore, regard 

 this form as the ethological type of the genus. In his " Verzeichniss " 

 (1894), Wasmann has taken great pains to record the names of the 

 host ants with which ferrugineus has been found, both by himself and 

 earlier authors. The regular host is unquestionably Formica fusca, 

 either alone or when living as an auxiliary, or slave with F. sanguined 

 or Polyergus rufescens. Less frequently the beetle occurs in the nests 

 of other European species of Formica, several species of Lasius, Tapi- 

 noma erraticum, My r mica scabrinodis and Leptothorax acervorum. 



Wasmann (1886) gives the following account of the behavior of 

 ferrugineus in nests containing fusca : "I believe that the ants are 

 quite indifferent to the beetle, as Forel, too, has remarked (" Fourmis 

 de la Suisse," p. 426). According to my observations Fo/yergus pays 

 no attention to it, and fusca little or none. The beetle, nevertheless, 

 is continually foisting itself on the ants. It scampers about among 

 them, climbing now on this individual, and over its back, now on that, 

 and anon allowing itself to be carried along passively on some ant's 

 back. It seeks out by preference the densest swarm of ants and climbs 

 from one to another. Polyergus seems to be unaware of its existence. 

 This ant neither starts nor moves her feelers or legs but behaves 

 as if the Hetcerius were not walking over her. Once only I saw a 

 Polyergus throw the beetle off, but the latter had run over her clypeus 

 just as she was about to clean her face with the strigil of her fore leg. 

 When a Polyergus encounters the beetle she takes no notice of it, and 

 this is usually also the case with fusca. Twice, however, I saw a fusca 

 touch the beetle's head and thorax with her mouth, but I was unable 

 to determine the nature of the contact as it lasted only a few seconds. 

 It was certainly not accidental. During this encounter the beetle ap- 

 plied its legs to its body and remained motionless, but hurried away 

 as soon as the ant withdrew her mouth. I repeatedly saw a fusca 

 take notice of one of the beetles. She approached it slowly, palpated 

 it from a distance with her antennae and then remained standing for 

 some time without touching it. Apparently she was in doubt about 

 the object and afraid to feel of it again. When a beetle crept about 

 on a fusca the latter sometimes (but rarely) , moved impatiently, but 

 did nothing more. The beetle feeds on dead and wounded ants. I 

 saw it repeatedly perched on the abdomen of such ants, boring with 

 its head and fore feet into a wound and remaining in this position for 

 some time." Wasmann (1908) made similar observations on aspeci- 



