Anastrepha ludens, the Mexican fruit fly or Mexfly, is a species of fly of the Anastrepha genus in the Tephritidae family (fruit flies). It is closely related to the Caribbean fruit fly Anastrepha suspensa, and the papaya fruit fly Anastrepha curvicauda. Anastrepha ludens is native to Mexico and Central America and is a major pest to citrus and mango agriculture in Mexico, Central America, and the lower Rio Grande Valley. The species exhibits high fecundity and relatively long lifespans compared to other species of fruit flies. These qualities make the Mexican fruit fly a particularly aggressive invasive species, especially threatening agriculture because the larvae grow and feed on many different species of fruit. The Anastrepha genus is designated as one of three genera that pose the greatest risk to American agriculture. According to the USDA, A. ludens is the only important member of the Anastrepha genus that is subtropical instead of tropical and thus has a range much further North than most Anastrepha species. Also the USDA estimates that the Mexfly causes $1.44 billion worth of damage in a 5-year time span, mostly to citrus farms. They are frequently designated as an invasive species in Southern California and Arizona and pose a serious threat to Florida's grapefruit agriculture. Description Adults Most species in the Anastrepha genus including A. ludens have a distinctive yellow and brown coloration of the body and wings. The adult A. ludens is 7–11 mm long, or slightly larger than a common house fly. They have a mesonotum that is 2.75-3.6 mm long and a wing span of 6.6-9.0 mm. Females have a relatively long life spans of up to 11 months. Males live even longer than females, up to 16 months. Female adult A. ludens have a long ovipositor (3.35-4.7mm) and sheath relative to body size and are capable of laying more than 1,500 eggs in their lifetimes, making A. ludens highly fecund. Anastrepha ludens have 12 chromosomes and most cells are diploid. A 2014 genetic study of A. ludens concluded that "A. ludens populations are genetically diverse with moderate levels of differentiation." They go on to attribute this genetic diversity to natural selection across the wide habitat range of the fly and to pest management practices. In addition they found high levels of inbreeding in the species. Gut bacteria exist in A. ludens called Enterobacteriacae (fruit fly type bacteria). Other families of bacteria have been