Recently Yahoo News on-line picked up the following:
The US has a plan to breed millions of flies and drop
them from planes. Here’s why (1/2)
Kameryn Griesser, CNN
Thu, July 10, 2025 at 3:27 a.m. PDT·7 min read
Hundreds of millions of flies dropping from planes in the sky might sound like a horrible nightmare, but experts say such a swarm could be the livestock industry’s best defense against a flesh-eating threat poised to invade the southwestern border of the United States.
An outbreak of New World screwworms — the larval form of a type of fly that’s known to nest in the wounds of warm-blooded animals and slowly eat them alive — has been spreading across Central America since early 2023, with infestations recorded in Panama, Costa Rica, Nicaragua, Honduras, Guatemala, Belize and El Salvador. Most Central American countries hadn’t seen an outbreak in 20 years.
The fly reached southern Mexico in November, sparking concern among US agricultural industry officials and triggering the closure of several border-area cattle, horse and bison trading ports.
It wouldn’t be the first time the US has had to battle these invasive bugs. The nation mostly eradicated the New World screwworm populations in the 1960s and 1970s by breeding sterilized males of the species and dispersing them from planes to mate with wild, female flies.
The strategy — essentially fighting flies with flies — slowly degraded the insects’ populations by preventing them from laying more eggs. Now, as the insects continue to spread north officials are hoping the approach could work again.
However, today only one facility in Panama breeds sterilized New World screwworms for dispersal, and hundreds of millions more sterile flies are needed to slow the outbreak, according to a June 17 letter from 80 US lawmakers.
The next day, the US Department of Agriculture announced plans to open a “fly factory” in a yet to be determined town near the Texas-Mexico border. But the process of defeating the screwworm may not be quick — or inexpensive.
Screwworm dangers
New World screwworms are the parasitic larva of a metallic
blue blow fly species called Cochliomyia hominivorax. Unlike all other blow
flies native to the Western Hemisphere, the New World screwworm feeds on the
flesh of living animals, rather than dead ones, said Dr. Phillip Kaufman, a
professor and head of the department of entomology at Texas A&M University.
The flesh-eating maggots go for most warm-blooded animals, including horses and cows.
They have also been known to infect domestic pets and even
humans in rare cases, Kaufman said.
“After mating, the female fly finds a living host, lands on its wound, and will lay up to 200 to 300 eggs,” Kaufman explained. “After 12 to 24 hours, those eggs all hatch, and they immediately start burrowing and feeding on the tissue of that animal, causing very, very large wounds to form.”
Since the outbreak began in 2023, there have been more than 35,000 New World screwworm infestations reported, according to statistics listed on the Panama–United States Commission for the Eradication and Prevention of Screwworm Infestation in Livestock (COPEG) website. Of those cases, cows make up about 83% of the affected animal species.
Treatment for infested cattle often involves cleaning, antiseptic treatment and coverings for the wounds, Lansford said.
If left untreated, the flies can kill an animal in a matter of one to two weeks and spread to others, posing a threat to the livelihood of ranchers.
“It’s a daily chore to provide those inspections to our livestock, just to make sure they’re not infested,” said Stephen Diebel, a rancher and the first vice president of the Texas & Southwestern Cattle Raisers Association. “We know the incredible economic impact an infestation would cause.”
There are no known vaccinations or effective repellant methods to prevent infestation, Diebel said. Instead, during warmer months, ranchers should avoid branding, tagging and other procedures that create potential entry points for the screwworms in livestock, he recommended. The tropical fly is less active in the winter.
While regional cattle trading is thought to be a major way the fly populations travel, Diebel said infestations can also affect wildlife such as deer, birds and rodents, making surveillance of the parasite’s spread even more challenging.
(to be continued)
Translation
美國計劃繁殖數百萬隻蒼蠅，並將其從飛機上投放。原因如下 (1/2)
數億隻蒼蠅從空中飛機上落下，聽起來像是一場可怕的噩夢，但專家表示，如此大規模的蒼蠅群或許是畜牧業抵禦即將入侵美國西南邊境的食肉動物威脅的最佳防御手段。
自2023年初以來，新大陸螺旋蠅疫情已在中美洲蔓延 - 蒼蠅的幼蟲會在溫血動物傷口中生長並慢慢將其食丢而聞名。疫情已在巴拿馬、哥斯達黎加、尼加拉瓜、洪都拉斯、危地馬拉、伯利茲和薩爾瓦多出現。大多數中美洲國家已有20年來從未爆發過疫情。
這種蠅類於11月抵達墨西哥南部，引發了美國農業官員的擔憂，並導致邊境地區多個牛、馬和野牛貿易口關閉。
這並非美國首次與這些入侵昆蟲奮戰。在1960年代和1970年代，美國透過繁殖該物種的絕育雄蠅，並將其從飛機上散播到野外，使其與野生雌蠅交配，從而基本上消滅了新大陸螺旋蠅群。
這種策略 - 本質上是以蠅治蠅 - 透過阻止昆蟲產卵，逐漸降低了昆蟲族群數量。如今，隨著昆蟲繼續向北蔓延，官員們希望這種方法能再次奏效。
然而，根據80名美國議員於6月17日致函稱，目前巴拿馬只有一家機構進行繁殖用於散播的絕育新大陸螺旋蠅，還需要數億隻絕育蠅來減緩疫情的爆發。
第二天，美國農業部宣布計劃在德克薩斯州和墨西哥邊境附近一個尚未確定的城鎮開設「蒼蠅工廠」。但消滅螺旋蠅的過程可能並非一蹴即就，或成本便宜。
螺旋蠅的危險
新大陸螺旋蠅 是一種名為Cochliomyia hominivorax的金屬藍色麗蠅的寄生幼蟲。德州農工大學昆蟲學系主任兼教授 Phillip Kaufman 博士說，與西半球所有其麗蠅不同，新大陸螺旋蠅 要進食活體動物的肉，而不是死體動物的肉。
這種肉食蛆會攻擊大多數溫血動物，包括馬和牛。
Kaufman說，已知到它們也會在極少數情況下感染家養寵物，甚至人類。
Kaufman解釋: 「交配後，雌蠅會找到活體宿主，落在宿主的傷口上，並產下多達200到300枚卵，」; 「12到24小時後，這些卵都會孵化，它們會立即開始鑽入宿主的組織中，造成非常大的傷口」。
根據德州動物衛生委員會副執行長兼助理州獸醫 Thomas Lansford 介紹，幼蟲用鋒利的嘴鉤啃食宿主的組織幾天后，會從宿主身上掉下來，鑽入地下，之後成長為成熟的蒼蠅。
根據巴拿馬-美國牲畜螺旋蠅感染根除和預防委員會 (COPEG) 網站上的統計數據，自2023年疫情爆發以來，已報告了超過35,000件新大陸螺旋蠅感染病例。在這些病例中，牛約佔受影響動物種類的83%。
Lansford表示，感染牛隻的治療通常包括清潔、消毒和包紮傷口。
如果不及時治療，這些蠅類會在一到兩週內殺死一頭牛，並傳播給其他牛，對牧場主人的生計構成威脅。
牧場主人、德克薩斯州和西南部養牛者協會第一副主席 Stephen Diebel 說: 「每天檢查牲畜，確保它們沒有感染，這是我們的日常工作」; 「我們知道感染會造成巨大的經濟損失」。
Diebel表示，目前還沒有已知的疫苗或有效的驅蟲方法可以預防感染。他建議，在溫暖的月份，牧場主應避免烙印、標記和其他可能為螺旋蠅創造潛在入口的措施。這種熱帶蠅類在冬季較不活躍。
雖然區域性牲畜貿易被認為是蒼蠅族群傳播的主要途徑，但 Diebel表示，蒼蠅的侵擾也會影響鹿、鳥類和囓齒動物等野生動物，這使得對寄生蟲傳播的監測更具挑戰性。
（待續）
Note:
1. Cochliomyia is a genus in the family Calliphoridae, known as blowflies (麗蠅 ), in the order Diptera. Cochliomyia is commonly referred to as the New World screwworm flies (新大陸螺旋蠅), as distinct from Old World screwworm flies. Four species are in this genus: C. macellaria, C. hominivorax, C. aldrichi, and C. minima. C. hominivorax is known as the primary screwworm because its larvae produce myiasis and feed on living tissue. This feeding causes deep, pocket-like lesions in the skin, which can be very damaging to the animal host. (Wikipedia)
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