Something I read on Julie Zickefoose’s blog yesterday brought back a memory from my high school years in Sebring, Florida, in the late ’50’s and early 60’s.

As you gain elevation in southern Florida, things generally go from swamps and marshes to agriculture such as vegetables and sugar cane.  The higher, better-drained ground tends toward citrus.  North and west of the lake lie the cattle ranches.  Most people don’t know it, but Florida produces more beef than any state except Texas.  The ranches begin just south and east of the Orlando area, extending around the west side of Lake Okeechobee and down toward Naples and Everglades City on the southwest coast.  Just about any part of Florida that will grow good forage and has a water table low enough for cattle to  find dry ground has been range land at one time or another.  Deseret Ranch, just west of the Melbourne area, is one of the largest ranches in the US at 300,000 acres (463 mi/sq).

But Florida is also prime screwworm country.

In some parts of the world it is not unusual to find a small child following the family buffalo or cow with a fly whisk.  This is only peripherally an act of kindness; its primary purpose is to kill or disturb screwworm flies and prevent them from laying their eggs.  Screwworms are the bane of cattle in tropical and sub-tropical regions around the world.  Without getting into the gory details, the fly lays eggs in open wounds, such as tick bites, wire scratches and so forth. After hatching, the larvae feast on beef, then drop off and burrow into the ground.  They emerge a few days later as adult flies and the process begins anew.  Since a single female can lay thousands of eggs over her one month lifespan, and wounds can receive multiple generations as they enlarge and are visited by more flies, an infestation is invariably fatal if untreated.

Range cattle, of course, can’t be followed around by small kids, and periodically rounding up and medicating them is impractical, so in the mid-50’s someone came up with a bright idea.  Millions of larvae would be grown in “factories,” and irradiated with gamma radiation, making them sterile.  They would then hatch into sterile adults, who would be released into the wild.  The sterile males would mate with fertile females, who would deposit sterile eggs.  Over time, the steadily increasing population of sterile flies would result in their breeding themselves into extinction.  After testing on the island of Curacao, the process was adopted in the US and later spread world-wide.

The airport six miles east of Sebring, one of the many training bases established in Florida during WW II, was the home of the Florida screwworm Eradication Program run by the U.S. Department of Agriculture.  The program was notable for bringing into the Sebring area some fine people, along with quite a lot of cash, and for one…other…thing.

Growning screwworm larvae requires giving them something to eat, and there arose the question of what?  In those days, there was still a source of large quantities of cheap mammalian flesh available: the whaling industry.

So it came to pass that hundreds of tons of whale meat were imported into the “Screwworm Factory” at the airport.  The flies would lay eggs on the meat, and the larvae would be zapped with radiation from Carbon 14.  They would then be released into the cattle-ranching areas in huge quantities.  It worked.  By 1966, screwworms had been eradicated north of the Mexican border, and by the dawn of the 21st Century in all of Central America.

But when the wind was right the good citizens of Sebring had lunches, dinners and other things interrupted by the aroma of all that rotting whale meat…one of the least fond memories of my youth.

Further reading:


A Personal Account of Programs to Eradicate the Screwworm (PDF)

1 thought on “SCREWWORMS

  1. The Florida Blogger

    Who knew this history. I used to be a high school sports writer for the Lakeland Ledger covering some Sebring football games. Would have never know this tidbit of information. Thanks for sharing.


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