Montana Updates Emergency Order to Prevent Spread of New World Screwworm

June 13, 2026 –Due to the evolving New World Screwworm (NWS) situation in Texas and the recent detection of a case in New Mexico, the Montana Department of Livestock (MDOL) has revised its emergency order to strengthen import restrictions on all animals entering Montana from Texas and New Mexico.

The Montana Department of Livestock (Department) is statutorily charged with exercising supervision to protect the livestock interests of the state from disease. Mont. Code Ann. § 81-1-102(1).

On June 3, 2026 the United States Department of Agriculture confirmed a case of New World Screwworm (NWS) (Cochliomyia hominivorax) in Zavala County, Texas. NWS is a fly that lays eggs in open wounds and orifices of any warm-blooded animal. The eggs hatch into larvae, which feed on living tissue causing severe injury to and potential death of infested animals. The fly was eradicated from the United States in 1966, and its reintroduction has the potential to cause significant economic damage to the livestock industry in the United States. As a pest of all warm-blooded animals NWS can infest all livestock species, wildlife, poultry and other birds, dogs, cats, and other small pets, as well as humans. After feeding in open wounds, larvae drop to the ground to pupate and later hatch into adult flies that go on to lay eggs and infest additional animals. Therefore, any movement of infested animals poses a risk of moving the fly to new areas where it could establish additional populations and sources of infestation.

Accordingly, the Department’s Animal Health Administrator/State Veterinarian has determined that circumstances exist constituting an imminent peril to animal health and welfare in the State of Montana and is issuing an emergency order stopping the entry of animals from states with NWS infestations until specific myiasis control measures have been met.

For purposes of this Order, the following definitions shall apply:

1. “Animals” means all warm-blooded animals, including cattle, horses, mules, asses, other equids, sheep, llamas, alpacas, bison, swine, ostriches, rheas, emus, goats, alternative livestock as defined in § 87-4-406, MCA, dogs, cats, rabbits, rodents, game animals, fur-bearing and wild animals, and poultry and other birds.
2. “Approved treatment” means a product for the treatment and/or prevention of NWS myiasis that is fully approved, conditionally approved, or has received an emergency use authorization (EUA).
3. “CVI” means a certificate of veterinary inspection and has the same definition as “health certificate” set forth in Admin. R. Mont. 32.3.201(1)(e).
4. “Infested zone” means a geographic area designated by the state animal health official (SAHO) of a state where NWS has been detected or by USDA and approved by the SAHO of a state where NWS has been detected. An area or zone is considered infested until state or federal officials declare freedom from NWS.1
5. “New World Screwworm” or “NWS” means the fly, eggs, pupae, or larvae of the genus and species Cochliomyia hominivorax.
6. “Official identification” or “ID” means:
7. For cattle, an official 840 RFID tag or an existing National Uniform Eartagging System (NUES) tag if placed prior to November 2024;
8. For sheep and goats, an official 840 RFID tag or a scrapie tag with both a flock number and individual animal number;
9. For swine, an official 840 RFID tag or a metal NUES tag;
10. For horses, a microchip or photographs of the horse (both sides and front);
11. For dogs and cats, a microchip or photographs of the pet (both sides and front);
12. For all other species, a microchip or other ID approved by the State Veterinarian.
13. “Originating from” means the animal has been physically present in the specified geographic area for any period of time beginning June 3, 2026.
14. “Restricted state” means a state that that has had a detection of NWS. A state is considered restricted for domestic movements until state or federal officials declare there are no active cases in the state.
15. “Wound” means any break in or injury to the integument, including the skin and mucous membranes. Wounds may include but are not limited to punctures, lacerations, other trauma, surgical locations, newly applied brands, tags, dehornings, the unhealed umbilicus of newborn calves, and females within 72 hours of birth.

Pursuant to Mont. Code Ann. § 81-2-102(1)(d), IT IS HEREBY ORDERED that:

1. In addition to the requirements below, all existing requirements for animals eligible for entry into Montana found in Title 32, chapter 3, subchapter 2 of the Administrative Rules of Montana remain in place, unless modified by this Order.
2. Animals originating from a restricted state may not enter Montana with a CVI issued prior to the initial detection of NWS in the restricted state and must comply with the requirements of this Order to be eligible for entry into Montana.
3. Equids from a restricted state may not travel to Montana on an extended equine CVI pursuant to Admin. R. Mont. 32.3.216(8).
4. To be eligible to enter Montana, all animals originating from:
5. an infested zone must have an import permit from the Department and a CVI documenting the following:
6. a copy of the movement permit or other official document supplied by the state of origin documenting that animals have met the state’s requirements to leave an infested zone;
7. the animals listed on the CVI have been administered an approved treatment no less than 72 hours and no more than 14 days prior to entry into Montana;
8. a statement confirming all animals listed on the CVI have been inspected and are free from wounds and evidence of NWS larvae infestation with;
9. the official identification of all animals listed on the CVI; and
10. the CVI is issued within 5 days prior to movement to Montana and after all other movement requirements have been met; or
11. a restricted state but outside of an infested zone:
12. a statement confirming all animals listed on the CVI have been inspected and are free from wounds and evidence of NWS larvae infestation with;
13. the official identification of all animals listed on the CVI; and
14. the CVI is issued within 5 days prior to movement to Montana.
15. Notwithstanding the requirements of paragraphs D and E, if any animal in a shipment intending to enter Montana is suspected of having a NWS infestation, no animals in the shipment may enter Montana until all animals have been treated as required by paragraph D.1.ii and all wounds have healed. 
16. For shipments of animals into Montana from an infested zone for immediate slaughter, please contact the State Veterinarian’s office for requirements.
17. For shipments of animals into Montana from an infested zone to an approved livestock facility in Montana, please contact the State Veterinarian’s office for requirements.
18. This Order is effective immediately.
19. This Order replaces Official Order No. 2026-01; however, Official Order No. 2026-01 remains in effect as to conduct occurring between June 3, 2026 and the issuance of this Order.

This Order may last no longer than five (5) years and is subject to review, modification, or annulment by the Board of Livestock. Mont. Code Ann. §§ 81-2-102(2) and 81-1-302. The Board of Livestock’s next regularly scheduled meeting is set for August 27, 2026. Official meeting information, including the agenda and public participation opportunities, will be available at https://liv.mt.gov/Board-of-Livestock/index when it becomes available.

DR. TAHNEE SZYMANSKI, DVM

Montana Department of Livestock

State Veterinarian and Animal Health Administrator

Montana Department of Livestock, Animal Health and Food Safety Division

Official Order No. 26-02

Source: Montana Department of Livestock