NURSING HABITS OF ANTS 299 



habit has been discovered quite recently, but since 

 it throws an unexpected light on the origin of the 

 intermediate castes that link worker and queen or 

 fertile and infertile workers together, and further 

 suggests how the relative numbers of these annectant 

 forms may be explained, we may refer shortly to this 

 aberrant habit. 



In most colonies of an ant (Formica sanguinea), 

 somewhat rare in this country, the extraordinary 

 spectacle may be seen of one or more foreign ant 

 species acting as slave-nurses more efficiently than 

 the indigenous workers with whom they either share 

 the household work or assume the nursing entirely. 

 Besides these slave-tenanted colonies there are some 

 in which a little cock-tail beetle has taken up its 

 abode. This visitant is not accidentally present, 

 but is deliberately reared by sanguinea-ants, appar- 

 ently for the sake of an ethereal drink which distils 

 from little yellow tufts placed on different points of 

 its body. This dram is solicited by the workers 

 applying their antennae to the cock-tail's body, 

 stroking it, and lapping the liqueur with their tongue. 

 The beetle-larvae are, however, not content to be 

 merely fed by the ant-workers, but ravage the colony, 

 eating up eggs and young, so that not only does the 

 state become impoverished and the nurses dissipated, 

 but the young ants receive insufficient nourishment 

 to convert them either into workers or queens, and 

 become stunted and unable to build, nurse, defend, 

 or extend the colony. Fortunately, however, the 



