Weaver ants or Green ants (genus Oecophylla) are eusocial insects of the family Formicidae (order Hymenoptera). Weaver ants are obligately arboreal and are known for their unique nest building behaviour where workers construct nests by weaving together leaves using larval silk. […] Oecophylla smaragdina found in Australia often have bright green gasters.

http://en.wikipedia.org/wiki/Weaver_ant Wikipedia
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