File:The American Museum journal (c1900-(1918)) (17973753659).jpg

Title: The American Museum journal
Identifier: americanmuseumjo04amer (find matches)
Year: c1900-(1918) (c190s)
Authors: American Museum of Natural History
Subjects: Natural history
Publisher: New York : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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THE AMERICAN MUSEUM JOURNAL SOCIAL PARASITISM AMONG ANTS.
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)N an article published in last year's volume of the Bulletin of the American Museum, the author called attention to the occurrence of certain very diminutive females, or queens, in a species of ant (Formica microgyria) from Colorado and Utah. Unexpected light was thrown on this interesting reduction in the size of the queen by a recent study in the Litchfield Hills (Conn.) of another ant (F. difjicilis) which is known to have similar queens. Several peculiar mixed colonies were found, each con- sisting of a fertile queen of F. difjicilis, either singly or accom- panied by a few young workers, living in colonies of another ant (F. incerta). Afterward the fact was established, both by observation of the natural colonies and by keeping the ants in artificial nests, that the difjicilis queen, being too small to bring up her own colony, enters a queenless colony of F. incerta, and then turns over her first batch of young to be brought up by the incerta workers. As the difficilis colony grows to be more and more populous, it gradually emancipates itself from the incerta and finally becomes a pure difjicilis colony, the workers of which are as bold and pugnacious as the queen and her first offspring were timid and conciliatory. These observations show that F. difficilis is a true cuckoo ant, a temporary parasite. All the mixed colonies of ants have hitherto been tacitly regarded as permanent unions or consocia- tions of two species, like the slave-making ants and their slaves, or auxiliaries. The case of F. difficilis throws light on a whole series of mixed colonies which have been called abnormal or accidental, merely because they have not often been seen, like the mixed colonies of Aphcenogaster tennesseense and A. fulvum; Formica exsectoides and F. subsericea; F. dakotensis and F. suhsericea; and the European as well as the American F. rufa and F. fiisca with their varieties. In all these cases it is highly prob- able that we are concerned with a normal temporary parasitism of one species of ant on another. The species of Formica which exhibit this method of founding their colonies all belong to the 74

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