Submitting New World Screwworm Samples

New World screwworm is a parasitic fly that lays its eggs in the wounds of warm-blooded animals, where the larvae feed on living tissue. This pest threatens livestock, pets, and wildlife, potentially causing severe animal suffering and economic losses if not detected quickly. You can help by monitoring your animals for signs and symptoms of New World screwworm and reporting any suspected cases.

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Request a collection kit

Livestock producers can request free sample collection kits and submit sample to the Arizona Veterinary Diagnostic Laboratory at no cost. Request a collection kit by contacting:

• Your local Extension office.
• Your large animal or equine veterinarian.
• The Arizona Department of Agriculture Animal Services Division.

Collect samples

1. If possible, take photos of the animal's wound and any larvae within the wound.
2. Use forceps to gently remove larvae of different sizes from several sites within the wound. Make sure samples are collected from the deepest tissue of the wound as these are more likely to be New Word screwworm. Each sample tube can hole 7 to 9 larvae.
3. Place 7 to 9 larvae in each of the two leak-proof vials (14-18 total larvae). Two samples from the same wound are needed as both the Arizona Veterinary Diagnostic Lab and a federal testing facility can conduct tests.
4. Vials in the collection kit are filled with 70% isopropyl alcohol. Make sure larvae are fully submerged in the vial. If needed, add more 70% isopropyl alcohol to the vials.
5. Complete submission label, including the animal ID, date and time of collection, collection address and/or GPS coordinates, collector's name and phone number.
6. Seal vials tightly to prevent leakage. Place both vials in the same sealed plastic bag with a submission label.
7. Place the sealed bag with vials and submission label into the other sealable plastic bag that contains cotton balls or another absorbent material.
8. Additional samples vials in their own labeled, sealable plastic bag can also be placed into the secondary bag.

Submit samples 

• Complete the sample submission form before sending your samples to the lab.
• Mail or drop off samples in person to the Arizona Veterinary Diagnostic Laboratory located at 2831 N. Freeway, Tucson AZ, 85705-5021.
• Shipping costs typically range from $6.95 to $10.70. Rates may be lower or higher depending on the vendor.

For questions about sample collection or submission, contact the Arizona Veterinary Diagnostic Laboratory at 520-621-2356.