Ants of the genus Solenopsis are common in urban environments due to their abilities to explore resources and to establish nesting sites, which helps their proliferation and also increases the occurrence of encounters with people and severe stinging. We aimed to increase understanding of this species in urban areas, so this study attempted to answer these questions: Are certain seasons more amenable to the founding of new colonies? Does colony size vary among seasons? What sites are used by these colonies in an urban environment? Observations were carried out every 2 weeks from May 2011 to Apr 2012 in Juiz de Fora, Minas Gerais, southeastern Brazil. For each active colony the site and the dimensions of the nest were registered. We showed that colonies of Solenopsis saevissima (Smith, 1855) were present in urban areas during the entire yr, with the highest incidence in the wet season, and nesting sites were associated mainly with vegetation. Because the dry season (Apr—Aug) was the period that had the smallest number of active colonies, this period could be considered the most favorable for area-wide control operations, but an individual mound treatment approach in the dry season should be take into consideration the occurrence of cryptic mounds.