Distribution and density of polygyne fire ants (Hymenoptera: Formicidae) in Texas.

Multiple-queen or "polygyne" Solenopsis invicta Buren colonies are a serious economic and environmental concern because they occur in much higher densities than the monogyne form. Polygyne colonies have been found at numerous locations in the United States; nevertheless, the frequency and distribution of this form are poorly known. Almost 700 roadside sites in 168 Texas counties were surveyed. Polygyny was discovered at 54% of the infested sites. Polygyne populations were scattered in a mosaic across Texas. The frequency of polygyny varied somewhat with geographic region, but the pattern was generally unrelated to habitat and environmental conditions. Polygyne sites averaged more than twice as many mounds per hectare as monogyne sites. Populations of monogyne and polygyne forms were slightly lower in cooler and drier portions of the state. Mounds of both forms were about the same size. Polygyny was correlated with lower rates of sexual production and reduced numbers of native ants. The high frequency of polygyny in Texas indicates that the fire ant problem in the state is much greater than previously realized.