THE SOCIAL INSECTS 



eat honey or ant grubs in observation nests. It does not seem 

 to attack the Formica brood, and the two sorts of ants take 

 very little notice of one another. It is really dependent on the 

 host only for shelter and protection, and is thus hardly a para- 

 site. Structurally, it shows few signs of degeneration, since 

 workers are numerous and have normal broad mandibles. 

 The male, however, is wingless and very worker-like in 

 appearance. There can therefore be no marriage flight, and 

 mating takes place on top of the Formica nest. 



The virgin queens are winged, and presumably the majority 

 of them fly off to found new colonies, after mating with their 

 wingless brothers. New colonies are founded in small cells 

 excavated on the edge of a Formica nest. The queen and 

 her young brood must move into the interior at a later stage. 

 In full established colonies, if the Formica moves its nest to 

 a new site the Formicoxenus follow them, carrying their own 

 brood. 



The various species of Strongylognathus are essentially 

 slave-makers, more dependent than the blood-red ant but 

 somewhat less so than the amazons. They have the charac- 

 teristic sickle-shaped mandibles of all the true parasites. One 

 species, S. huberi, which is found in Switzerland, is known 

 to make raids to obtain the brood of the ant Tetramorium 

 caespitum. The raids are apparently made at night when the 

 Tetramorium are less active and less resistant to aggression. 

 The case is unusual in that some Tetramorium slaves may 

 take part in the raids, but few observations on the subject 

 have so far been made. While the Tetramorium slaves are 

 necessary for rearing the brood, the Strongylognathus may 

 do some of the work of nest-construction. Another species, 

 S. testaceus, is quite common in parts of western Europe and 

 is more degenerate. The worker caste is never numerous 

 and seems to be on the way to disappearance. It does not 



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