36 
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[Vol. 95 
between two nests of C. cursor, this could have been during a bud- 
ding period. After budding the sister colonies keep contact and 
numerous exchanges are possible. Sometimes the smaller colony 
continues to reinforce itself. As a consequence of this form of dis- 
persal, colonies in the same habitat are probably kin. This explains 
the fact that some displaced workers can be adopted into an alien 
colony, and that nurses and callows found on the surface are trans- 
ported by foragers into the nest (cf par. 5). This result has also to be 
related to the adoption experiments conducted in the laboratory by 
Nowbahari and Lenoir (1984): 50% of the workers introduced into 
an alien colony are adopted if they originate from the same habitat. 
This is surprising for monogynous species which are generally con- 
sidered to have closed societies (Holldobler and Wilson 1977). 
Readoption of newly inseminated females is not exceptional in 
polygynous species, for example in mound-building Formica, Iri- 
domyrmex humilis, Monomorium pharaonis, Myrmica ruginodis 
microgyria, Lasius sakagamii (see Holldobler and Wilson 1977, 
Rosengren and Pamilo 1983, Yamauchi et al. 1981). Budding is 
usual in polygynous social insects like termites as discovered by 
Grasse and Noirot (1951) in Anophotermes and Trinervitermes. 
These authors called the phenomenon Sociotomy: a fragmentation 
of the society in different parts where the castes are represented and 
which can reproduce a complete society (Grasse 1984). New data are 
available on Nasutitermes (Thorne 1982, 1984; Roisin and Pasteels 
1986a, b). Budding is exceptional in wasps where it is known only 
for Polybinii (Evans and West-Eberhard 1970, Spradberry 1973). 
Budding seems also to exist in social spiders ( Agelena consociata, 
Darchen 1978; Achaeranea wau, Lubin and Robinson 1982). In ants 
it is found in polygynous and polydomous species like Lasius saka- 
gamii (Yamauchi et al. 1981), the Formica rufa group (F. aquilonia 
and F. polyctena (Mabelis 1979, Rosengren and Pamilo 1983) and 
in Leptothorax curvispinosus (Stuart 1985). It occurs also in Pone- 
rinae lacking a reproductive caste like some Rhytidoponera species, 
or Ophtalmopone berthoudi, where workers are inseminated (Cro- 
zier et al. 1984, Peeters and Crewe 1984, Pamilo et al. 1985). Tra- 
niello (1982) pointed out that budding could exist in Amblyopone 
pallipes but precise observations are missing. Budding is the rule in 
Dorylinae army ants: the colony reproduces by binary fission, one 
group containing the old queen and the other the successful daugh- 
ter queen (Schneirla and Brown 1950, Raignier and van Boven 1955, 
