New World screwworms arrived in Texas this summer, for the first time since 1976
THE NUMBERS: U.S. invasive-species agency staffing, in FTEs* –
|
FY2025 |
FY2026 |
FY2027 request |
| National Marine Fisheries Service |
3,089 |
2,441 |
1,806 |
| Animal and Plant Health Inspection Service |
8,462 |
8,189 |
8,129 |
| U.S. Fish and Wildlife Service |
8,759 |
7,784 |
5,861 |
| U.S. Geological Service |
7,718 |
6,696 |
4,736 |
| National Park Service |
18,541 |
16,039 |
13,598 |
* “Full-time equivalent employees,” the standard measure of agency staffing. Data from agency budget justifications; links below.
WHAT THEY MEAN:
Since the early-June sighting of a New World screwworm in Zavala, TX — America’s first since 1976 — the bugs have turned up in 16 Texas counties and one New Mexico site. A gross but to-the-point look at this unpleasant insect, from the Centers for Disease Control:
“The New World screwworm (NWS), or Cochliomyia hominivorax, is species of parasitic fly that completes part of its lifecycle by feeding on the tissue or flesh of warm-blooded animals and people. NWS flies are attracted to wounds and body openings like the nose, eyes, ears, and mouth, where they lay eggs. The eggs hatch into maggots (larvae) that eat live tissue, causing a worsening, often painful, and foul-smelling wound. NWS is typically found in South America and parts of the Caribbean. However, the fly has steadily moved northward from South America through every country in Central America, Mexico, and the United States since 2023.”
Pulling back a bit: If they’re now endemic to the U.S., screwworms would be one among 6,500 “invasive species” resident in North America — that is, animals, plants, fungi, microorganisms, etc., arriving in the continent since European settlement in the 1500s. (The native-species count is about 250,000.) Some invaders — say, feral horses — are benign; some, like indoor centipedes, are harmless even though creepy and annoying. Others, like the Burmese pythons in Florida’s wetlands or Asiatic and European earthworms in the Minnesota woods, pose risk to habitat and native wildlife. And a few, like the zebra mussel in the Great Lakes and the screwworm, threaten the economy, public health, or both.
What can be done about them? Some useful international agreements help stop new ones from getting here. As an example, the 2017 International Ballast Convention requires commercial vessels to ditch ballast water in mid-ocean to prevent transcontinental movements of shallow-water clams, shrimp, mussels, seaweed, and fish.
Extirpating invaders after arrival is much harder. Referring to the tens or even hundreds of thousands of Florida pythons, the U.S. Geological Survey sadly concedes that “the odds of eradicating an introduced population of reptiles once it has spread across a large area are very low.” But “very low’ isn’t the same as “impossible” — the New World screwworm itself, in fact, was once a success story, eliminated from the U.S. in 1966 by the release of sterilized male flies in infested zones. And even if eradication is impossible, “containment” is a lot better than “uncontrolled spread.”
All three options — prevention, eradication, containment — require investment in science and human talent in the field. That’s been the job of a battery of high-performance U.S. scientific agencies — the USGS and the Fish and Wildlife Service on remote lands and waterways; the National Marine Fisheries Service in seaports and coastal waters; the Animal and Plant Health Inspection Service at airports and border crossing-points; the National Park Service — who do their best to stop invaders at the border, identify new populations, and slow them down once they’ve arrived.
Disinvestment in science and human talent — the trend of the last two years — means more invaders will get through, fewer new populations will be caught early, and new arrivals will do more harm. The Trump administration’s ill-starred “DOGE” experiment last year cut the combined APHIS, NMFS, USGS, and FWS staff by nearly 5000 (from a base just above 28,000), with an especially high toll on young talent. This year’s parent-agency budgets envision cutting 3,360 more positions. The larger National Park Service is down about 2,000 (from 18,000), and the administration hopes to scrap 2,920 more. Local-level impact ranges from scaled-back inspection of incoming cargo at Los Angeles ports and the proposed cancellation of a planned Illinois barrier against Asian carp entry to Lake Michigan, to closure of a Flathead Valley (Montana) U.S. Geological Survey research program on zebra mussels.
Altogether, the U.S. government has diminished scientific capacity, fewer scientists, and less investment in inspection and infrastructure than it had in the summer of 2024. Budgeting proposals suggest continued DOGE-like staff cuts and general bias against the “discretionary spending” budgets scientific agencies need to fulfil their missions and recruit young talent. Against this backdrop, this summer’s Texas screwworms (like, in similar contexts, Pennsylvania’s measles-associated deaths and the spring’s lettuce-borne Cyclospora outbreak) seem less “an unfortunate specific incident” and more “a sign of what’s to come.”
FURTHER READING
Policy overview:
U.S. government invasive species gateway.
Doing their best in adversity: Invasive species policy summaries from the U.S. Geological Survey, the Fish and Wildlife Service, the National Marine Fisheries Service, National Park Service, and Animal and Plant Health Inspection Service.
The International Maritime Bureau explains the International Ballast Convention.
Screwworms:
From APHIS, a description of the fly & the larval worm.
Via CDC, a map of New World screwworm “infested zones” in Texas.
New Mexico’s Department of Agriculture hopes to stop the spread.
Agency staffing:
Animal and Plant Health Inspection Service: FY2025 and FY2027 budget justifications. This year’s requests is down by 60 staff. (More technically, per typical budget usage, 45 “FTE,” full-time equivalent employees.)
National Marine Fisheries Service: FY2025 and FY2027 budget justifications. The 2027 request is down 635 FTEs.
Fish and Wildlife Service: FY2025 and FY2027 budget justifications, with 484 fewer proposed FTEs.
U.S. Geological Service: FY2025 and FY2027 budget justifications, with 1,960 fewer proposed FTEs.
National Park Service: Budget justifications from FY2010 forward, with a proposed 1,441-FTE cut.
Budget big picture:
U.S. fiscal problems originate in aging, tax policy, health insurance, and interest payments. Less “discretionary” spending cannot solve them. In the specific case of science and medicine, disinvestment in vaccination, food safety, and invasive species control typically brings the opposite fiscal-policy result: tiny savings, then larger remediation bills later on. PPI’s 30-year model budget (2024) explains the looming fiscal crisis and the right way to meet it.
And some more invaders:
Earthworms: The suburban gardener loves to see him/her*; the northern forestry manager reacts with consternation and fear. All earthworms north of the Mason-Dixon line are invaders — the last Ice Age froze off all the locals — and in the woods they’re not benign. From the Minnesota Department of Natural Resources:
“All of the terrestrial earthworms in Minnesota are non-native, invasive species from Europe and Asia. … Minnesota’s hardwood forests developed in the absence of earthworms. Without worms, fallen leaves decompose slowly, creating a spongy layer of organic ‘duff’. This duff layer is the natural growing environment for native woodland wildflowers. It also provides habitat for ground-dwelling animals and helps prevent soil erosion. Invading earthworms eat the leaves that create the duff layer and are capable of eliminating it completely. Big trees survive, but many young seedlings perish, along with many ferns and wildflowers.”
The 15 worm species in eastern Canada, New England, New York, and the Midwest, mostly descendants of European worms brought in after the Mayflower landing, are chewing their way through the duff layers of the north woods at about 50 feet per year. The newest, the “Asian jumping worm” (a Korean/Japanese native, present on the West Coast since the 19th century), first turned up in Minnesota in 2006 and reached Wisconsin in 2013. Earthworm basics and advice from Minnesota’s Forestry and Wildlife Extension Service.
* Him/her is the correct pronoun; earthworms are naturally hermaphroditic.
Islands: In Hawaii, 282 of 1100 native species are threatened or endangered. Hawaii’s Invasive Species Council.
Lakes: Michigan’s Asian carp planning council tries to keep the carp out of the Great Lakes.
Spiders: The University of Georgia tentatively concludes that Joro spiders — very large web-weavers, native to Japan, present in Georgia since 2014 — are proving compatible with local arachnids and insects.
ABOUT ED
Ed Gresser is Vice President and Director for Trade and Global Markets at PPI.
Ed returns to PPI after working for the think tank from 2001-2011. He most recently served as the Assistant U.S. Trade Representative for Trade Policy and Economics at the Office of the United States Trade Representative (USTR). In this position, he led USTR’s economic research unit from 2015-2021, and chaired the 21-agency Trade Policy Staff Committee.
Ed began his career on Capitol Hill before serving USTR as Policy Advisor to USTR Charlene Barshefsky from 1998 to 2001. He then led PPI’s Trade and Global Markets Project from 2001 to 2011. After PPI, he co-founded and directed the independent think tank ProgressiveEconomy until rejoining USTR in 2015. In 2013, the Washington International Trade Association presented him with its Lighthouse Award, awarded annually to an individual or group for significant contributions to trade policy.
Ed is the author of Freedom from Want: American Liberalism and the Global Economy (2007). He has published in a variety of journals and newspapers, and his research has been cited by leading academics and international organizations including the WTO, World Bank, and International Monetary Fund. He is a graduate of Stanford University and holds a Master’s Degree in International Affairs from Columbia Universities and a certificate from the Averell Harriman Institute for Advanced Study of the Soviet Union.
