The fecundity of queens of Iridomyrmex humilis (Mayr) as mesaured by an oviposition test in isolation was correlated with their weight, The relative attractiveness of queens to workers was not correlated with either their weight or fecundity. Comparison of these results with those on other ant species show that queens of I. humilis have a relatively low level of attractiveness. This low attractiveness may result from the high number of queens per nest in I .humilis. This hypothesis is supported by the comparison of the attractiveness of queens in experimental monogynous and polygynous colonies which showed that queens in monogynous colonies have a higher attractiveness to workers. As a consequence of their higher attractiveness, queens in monogynous colonies probably receive more food. This may partially explain the higher weight and fecundity of queens in monogynous colonies. These results are dicussed with regard to some implications of polygyny