APHIS-International Programs Action Programs Staff maintains sterile fly breeding facilities for both Mexfly and Medfly where flies are irradiated (made sterile) and then released to breed with native fly populations, effectively reducing the flies' populations. The program is cooperatively funded with countries who also desire fly control and allows an effective barrier to reduce the threat of re-introduction of these harmful species to the United States through agricultural trade.
The Mexican Fruitfly Anastrepha ludens or "Mexfly" is a fly species native to Mexico and is of quarantine importance to the Caribbean. Newly hatched larvae eat and burrow into the pulp of fruits, taking on the color of their food so that when they are small they are easily overlooked. Many maggots may be found in a single fruit. Mexfly is rare in Florida but commonly found in Texas and California.
The Mediterranean Fruit Fly Ceratitis capitata or Medfly is another form of fruitfly also capable of causing extensive damage to a wide range of fruit crops. It is native to the Mediterranean area but has spread invasively to many parts of the world including Australasia and North and South America. Medfly is of particular concern to fruit-growing regions including the State of California as it can cause significant negative economic impact due to fruit loss and the fly's quick invasive capability.