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Reemergence of New World Screwworm in North America: Fly and Animal Resources

Understanding the Fly

Eggs:

Are laid by adult flies in wounds, and if observed, should be removed by a professional to ensure nothing is missed.

Larvae (maggots): This lifecycle stage is parasitic and causes infection in the host.

NOTE: This is the stage that will inform public health professionals of the flies’ presence.

    • Larvae should never be discarded in the trash, as this may support their lifecycle development into adults.

Pupae: Will drop from the animal host and mature in the ground to become adults.

    • This is why suspect animals should not be relocated.

Adult Fly: After mating, females will seek out the next animal host to lay eggs on.

Fly Identification and Life Cycle

The New World screwworm adult fly is identifiable by its large orange eyes, yellow face, metallic blue body, and the three stripes along its back.

Health

Infection Observation

Wildlife Animals

  • Observe open sores, animal irritation, or foul odors.
  • Deer, rabbits, turkeys, and small mammals are commonly impacted.

Primary Agency: Texas Parks and Wildlife Department

Phone: (512) 389-4505

  • Take photos of the animal.
  • Write down location details.
    • GPS coordinates are best. 
    • Any details can support surveillance.
  • Do not attempt to handle any live or dead animals.

Domestic Animals & Livestock

  • Check animals daily for wounds.
  • Contact a vet immediately if you are concerned.

Primary Agency: Texas Animal Health Commission

Phone: 1-800-550-8242

  • Do not relocate the animal.
  • Do not attempt to remove eggs or larvae.
  • Do not discard eggs or larvae.

Prevention

Prevention: For the prevention of New World screwworm in animals, please visit USDA APHIS New World Screwworm Information. Additionally, consider protecting domestic pets from NWS exposure. For information on prevention, diagnosis, and treatment options, visit FDA New World Screwworm Information for Veterinarians.

Notification of Mosquito Vector Control

Please contact the Harris County Public Health Mosquito & Vector Control Division if you have questions about the fly, larvae, or need to report a suspected animal or insect case of New World Screwworm at: Phone: 1-713-440-4800 or Email: [email protected]

URGENT: Do not throw any live maggots in the trash or outside. Do not move animals with maggots into new areas as either of these actions could result in NWS spreading.