found in Mexican fruit flies including Vibrionaceae, Bacillaceae, Micrococcaceae, and Pseudomonadaceae. The effects of these bacteria on A. ludens are not well studied but it has been proposed by M. Aluja that A. ludens regurgitate internal bacteria onto their host and use the bacterial colonies as a protein source. The gut bacteria may also play a role in digestion and detoxification of chemicals. Larvae Larvae have an elongated cylindrical shape typical of fruit flies and are white in color. Larvae can be up to 12 mm in length. Larvae usually pupate on the ground but have also been observed to occasionally pupate inside its host fruit. Larvae determine when to exit a fruit through physical and chemical signals such as the pH of the rotting fruit and the drop of the fruit from to the ground. Distribution Anastrepha ludens is native to Guatemala, Mexico and possibly Costa Rica. It is an invasive species to the US. The first record of these flies spotted outside of their native habitat of Mexico and Central America was in a small Texas colony in 1903. By 1927, Mexican fruit flies were infecting citrus farms in lower Rio Grande Valley of Southern Texas and threatening farmland in California, Texas, Florida, and Arizona. In 1954, the fly species had spread westward as far as Hermosillo. A. ludens were rare in Costa Rica until the 1990s when they suddenly appeared on citrus plants. It is unclear if the species was native to Costa Rica or migrated there from the north. It was previously believed that the species is native to Colombia because of misidentification of Anastrepha manizaliensis but it is now known that the species does not exist there. The US Department of Agriculture presumes that these flies were introduced to the USA through the import of larvae infested fruits. Currently, California, Arizona, Florida and most of northern Mexico are considered free of Mexican fruit flies and eradication efforts are taking place in Texas, with some Texas quarantine areas having been successfully cleared and the quarantines lifted. The eradication of these flies from most of the US and Northern Mexico is largely due to the successful implementation of the sterile insect technique (SIT). SIT is currently used in parts of Texas to control the species population. Habitat The Mexican fruit fly prefers living near citrus and other fruits, which act as hosts where the female can lay