New UF/IFAS document profiles destructive screwworm fly recently detected in Florida Keys


GAINESVILLE, Fla. — To educate Florida agricultural producers, livestock owners, pet owners and concerned residents about the destructive screwworm fly recently detected in the Florida Keys, experts with the University of Florida Institute of Food and Agricultural Sciences have published a profile on the insect, available online at

The free resource provides a scientific overview of Cochliomiya hominivorax, commonly known as the primary screwworm fly or New World screwworm fly, said Jack Payne, UF senior vice president for agriculture and natural resources. The species was a major challenge for Florida ranchers until the late 1950s, when it was eradicated from the state with controlled releases of sterile male flies.

“Since the announcement earlier this week that this pest had re-emerged, we’ve had people working virtually around the clock to get accurate information to producers, pet owners and the public – this document is yet another example of UF/IFAS at work,” Payne said. “Knowledge is power, and state residents can aid the eradication effort by learning to recognize the symptoms of infection.”

A member of the blow fly family Calliphoridae, the primary screwworm fly is a threat to warm-blooded animals, including people, because its larvae feed on living tissue to develop, said Jennifer Gillett-Kaufman, an associate Extension scientist with the UF/IFAS Entomology and Nematology Department and one of the profile’s authors.

Adult female flies deposit eggs on superficial wounds or mucous membranes in host animals, creating infections that may draw other females that lay additional eggs, increasing the parasite burden on the host, she said.

“This insect has a truly fearsome reputation because the larvae will expand existing wound sites and the process may continue until the host animal is treated or it dies,” Gillett-Kaufman said. “Fortunately, this species has a biological Achilles’ heel – the adult females mate only once during their lives, and that enables scientists to eradicate local populations by releasing sterile male flies that mate with females who then produce no offspring.”

Gillett-Kaufman noted that state and federal officials are preparing to release sterile male flies in the affected Florida Keys, which are under quarantine.

The profile includes descriptions of the primary screwworm fly’s distribution, physical appearance, life cycle and medical and veterinary importance. It also contains material addressing management of the fly, management of potentially infected livestock or pets, contact information for owners of potentially infected animals, and a list of reference publications spanning eight decades of scholarship.

Although the primary screwworm fly has been absent from Florida for a half-century, the authors were able to gather information quickly because the species has been studied and discussed extensively in entomological lore, Gillett-Kaufman said.

The profile is part of the long-running “Featured Creatures” series published by the UF/IFAS Entomology and Nematology Department, and was written by Gillett-Kaufman, veterinary entomologist Phil Kaufman, an associate professor with the department, and deer expert Samantha Wisely, an associate professor with the UF/IFAS Department of Wildlife Ecology and Conservation.

In addition, the profile is available from the UF/IFAS online Extension library, the Electronic Data Information Source, or EDIS, Payne said.

“My hat’s off to our team of authors and, indeed, to everyone involved in this fight,” he said, “from our UF/IFAS Extension faculty to the Florida Cattlemen’s Association and other industry organizations, to our colleagues at state and federal agencies. We are united in purpose and we will prevail.”



Writer: Tom Nordlie, 352-273-3567,

Sources: For interview requests, please contact Tom Nordlie at 352-273-3567 or after hours at 352-375-1415 or

Photo by Lyle Buss, UF/IFAS


Posted: October 6, 2016

Category: Agriculture, Invasive Species, Livestock, Pests & Disease, UF/IFAS
Tags: Entomology And Nematology, Gillett-kaufman, Kaufman, Payne

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