International Screwworm Eradication Program Records

The Screwworm Eradication Program includes U.S. domestic and international agricultural programs to eliminate the New World screwworm (Cochliomyia americana) from the North American continent. A flesh-eating pest of warm-blooded animals, the screwworm was brought under control using Sterile Insect Technique, which emphasizes biological control methods. The technique used in screwworm eradication involves raising large numbers of sterile flies in production facilities. The sterile flies are then released into the wild fertile population to overwhelm and eliminate it through interbreeding.

Below is a timeline of U.S. Department of Agriculture (USDA) screwworm research highlights.

1858: First reported screwworm cases on Devil's Island, French Guiana

1933: Emory Clayton Cushing and Walter S. Patton recognized screwworm fly as its own species, Cochliomyia hominivorax (different from the blowfly species)

1934: USDA Agricultural Research Service (ARS) established research station at Valdosta, Georgia (closed 1936) to conduct research on screwworms by scientists Ernest William Laake and Edward Fred Knipling

1935: ARS secured funding for research on screwworms. Raymond C. Bushland began research on artificial diets for rearing screwworms.

1937: Bushland and Knipling are transferred to ARS laboratory in Menard, Texas. Bushland began research on controlling screwworms through chemical means. Knipling began research on sterile male technique, an autocidal theory of total insect population management.

1938: USDA developed Smear 62, an insecticidal wound treatment

1939: Bushland is transferred to Orlando, Florida, to conduct research on mosquito control

1940: Knipling is transferred to Orlando, Florida, to conduct research on insects affecting man

1946: Bushland transferred to ARS laboratory in Kerrville, Texas. Knipling transferred to USDA-ARS headquarters in Washington, D.C.

1950: Arthur W. Lindquist introduced Knipling to Hermann Joseph Muller's research on genetic mutations in fruit flies by radiation. Bushland and Donald E. Hopkins began tests on sterilization of screwworms using radiation.

1951: Alfred H. Baumhover arrived at Kerrville, Texas, to work on screwworm eradication using sterile male technique. Sanibel Island, Florida, was the first field test to use the sterile male technique.

1954: Baumhover traveled to Curacao, Netherlands Antilles, and began successful screwworm eradication campaign using sterile male technique

1955: Baumhover returned to Orlando, Florida, to work on eradication of screwworms from the Southeast United States. Mass rearing techniques were developed.

1955-1957: A mass fly production facility for rearing screwworms is built in Bithlo, Florida. Screwworms successfully eradicated in a 2000 square mile field test area near Orlando, Florida.

1958: ARS built mass fly production facility near Sebring, Florida

1959: Screwworms successfully eradicated from the Southeast United States

1962: ARS Southwest United States screwworm eradication program began with flies produced at the Kerrville, Texas, ARS laboratory. Mass production facility built at Mission, Texas.

1963: ARS developed program specializations. Billy Gene Hightower studied screwworm ecology in Texas. Alfred H. Baumhover studied sterile fly distribution. Leo E. LaChance studied screwworm genetics. Maxwell M. Crystal studied chemosterilants.

1964: Baumhover transferred to Oxford, North Carolina, to work with the Tobacco Insects Investigations

1966: USDA declared screwworms eradicated from Southwest United States, except Texas continued to be infested until 1982. United States and Mexico conducted a feasibility survey for a screwworm eradication program in Mexico, which resulted in the establishment of a screwworm eradication program in Mexico.

1974: The Lincoln-Eden Report, "The Southwestern Screwworm Eradication Program: A Review," is published. Charles G. Lincoln and William Gibbs Eden were tasked with evaluating the Southwestern United States Screwworm Eradication program after poor results spanning 1972-1974. They concluded that the program was a success despite some minor faults and the research should continue.

1977: The ARS Screwworm Research Unit relocated from the Mission, Texas, laboratory to a sterile fly production facility near Tuxtla Gutierrez in Chiapas, Mexico

1984: A new gelled diet is developed by ARS for use in mass rearing screwworms

1990: "Severn Run's Cazador," a German wirehaired pointer, is trained by John Bertram Welch to detect screwworm larvae and screwworm infested animals

1991: Mexico was declared screwworm free

1994: Screwworms eradicated from Belize and Guatemala. Panama City, Republic of Panama, became the headquarters for the USDA-ARS Screwworm Research Unit.

1995: Screwworms eradicated from El Salvador

1996: Screwworms eradicated from Nicaragua

1999: Screwworms eradicated from Honduras

2000: Costa Rica declared screwworm free