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Severn Run's Cazador (Caz), Screwworm Detection Dog, Collection: Screwworm Eradication Program Records


The Severn Run's Cazador (Caz), Screwworm Detection Dog, Collection: Screwworm Eradication Program Records is part of the larger Screwworm Eradication Documentation Project--the U.S. Department of Agriculture's (USDA) landmark employ of SIT (sterilized insect technique) for "area wide integrated pest management." The Severn Run's Cazador Collection includes two boxes of materials documenting the first dog trained to detect the presence of screwworms (Cochliomyia hominivorax). The materials span the years 1989-2000.

This collection was extracted from materials donated in 2000 by John Bertram Welch, Cazador's owner and handler. At the time of donation Welch was the American director of the Mexican-American Commission for the Eradication of Screwworm in Chiapa de Corzo, Chiapas, Mexico.

The records were arranged and described by Emelie M. George in 2003, while a graduate student working towards her Master's of Library Science at the University of Maryland, College Park.

Finding Aid File


Historical Sketch

Severn Run's Cazador served as part of an experiment for the U.S. Department of Agriculture's (USDA) Screwworm Eradication Program. USDA scientist John Bertram Welch wanted to see if a dog could be trained to sniff out animals that were infested with screwworms, as well as to find screwworms that had fallen out of wounds, crawled into the ground, and pupated.

Welch contacted the U.S. Customs Service's Detector Dog training facility in Front Royal, Virginia, for assistance. Dog breeders Lawrence and Patricia Huntington were intrigued with the concept and donated an animal to Welch. The choice was Cazador, an American Kennel Club (AKC) Registered German Wire-haired Pointer, who was born on July 26, 1985, at the Huntington's Severn Run's Kennel in Annapolis, Maryland.

Cazador began his training in 1988. After five months, Cazador was able to successfully detect infested animals. He could detect the pupae in the ground after three more months. His unique abilities and enthusiastic personality made him a treasured member of the Screwworm Research Unit in San Jose, Costa Rica. Cazador was Welch's constant companion, traveling with Welch and giving demonstrations. Cazador worked primarily in Costa Rica, Mexico, Panama, and Texas.

The media was intrigued by Cazador and his talents for detecting screwworms. A number of stories about the dog appeared in newspapers, magazines, and on television, including a documentary about him in Germany. The USDA is not currently using any screwworm detector dogs, but in the future, the Panama program may train some dogs for use in the barrier zone.

Scope and Content Note

John Bertram Welch, a U.S. Department of Agriculture (USDA) entomologist, collected these materials to document the work of Cazador, the screwworm detection dog for the USDA Screwworm Research Unit. The majority of the materials are artifacts, such as leashes, employee identification tags, and a harness. Also included are approximately 20 letters of condolence that were emailed to Welch after Cazador's death in 2000. The collection contains photographs and slides of Cazador and Welch in the field. Miscellaneous materials in this collection include a short biography of Cazador, written by Welch, a scientific journal article on using dogs to detect screwworms, and a photocopy of Cazador's birth certificate.

Materials relating to the research areas where Cazador was working are located within the Promotional Materials: Screwworm Eradication Program Records (Collection 214) and the Southwestern United States and Mexico Collection: Screwworm Eradication Program Records (Collection 211).

Series Description

Series I. Correspondence. 1989-2000. .25 box.

Correspondence and veterinary records relating to Cazador's work in Panama and Costa Rica in the early 1990s are included in Series I. There are also approximately 20 letters of condolence to John Bertram Welch after Cazador's death in 2000.

Series II. Miscellaneous. 1990-2003. .25 box.

Miscellaneous materials include a photocopy of Cazador's birth certificate, three articles on using dogs for screwworm detection, including one written by Welch for the Journal of Economic Entomology (1990), a pamphlet on using dogs for termite detection, two short biographies on Cazador written by Welch, and a small sign printed with Cazador's name.

Series III. Visual Materials. 1989. .5 box.

Series III contains three black and white 6 1/4" x 9 3/4" photographs taken in Costa Rica in 1989. The photographs show Cazador by himself, Cazador with Welch, and Cazador picking up the scent of screwworm infested sheep. The series also includes two CD-ROMs containing photographs of Cazador and Welch in the field, labeled by Welch. There are also approximately 100 color slides, which duplicate some of the photographs on the CD-ROMs, copies of photographs, and 3 black and white contact sheets.

Series IV. Memorabilia. 1994, 1999. 2 boxes.

Memorabilia materials include Cazador's ashes, three leashes, three employee identification badges, and one leather harness.


Information for the Historical Sketch and the Scope and Content Note was taken from the following sources:

Promotional Materials: Screwworm Eradication Program Records. Manuscript Collection 214. Special Collections, National Agricultural Library.

Severn Run's Cazador (Caz), Screwworm Detection Dog, Collection: Screwworm Eradication Program Records. Manuscript Collection 310. Special Collections, National Agricultural Library.

Special Collections, National Agricultural Library. "STOP Screwworms: Selections from the Screwworm Eradication Collection." Accessed October 14, 2003 from

Southwestern United States and Mexico Collection: Screwworm Eradication Program Records. Manuscript Collection 211. Special Collections, National Agricultural Library.

Welch, John Bertram. USDA personnel website. Accessed October 14, 2003 from

Historical Sketch

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

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