Recently the imported fire ant, Solenopsis invicta, has reached ranchlands in the brush country of South Texas well beyond the main distribution of dense populations. These invasions into wildlife habitat apparently have been promoted by the transport of ant colonies in nursery products to the newly landscaped shopping malls and warehouses of urban areas like Laredo. From that foothold, the ants colonize margins of stock ponds and creek bottoms on nearby ranches. Presence of the South American fire ant in South Texas provides an opportunity to establish populations of their native parasitoid phorid flies (Pseudacteon spp.) under sub-tropical conditions. Our observations have suggested ways to minimize the likelihood of colonization by S. invicta or increasing the opportunity to stop an invasion by early detection and local treatments.