1. What is the New World screwworm?
Answer:
The New World screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae (maggots) feed on living tissue in wounds of warm-blooded animals. Unlike other maggots, they burrow deeper and can cause serious injury or death if not promptly treated.
2. Why is there renewed concern about screwworms?
Answer:
While eradicated in the U.S. in the 1960s, screwworms have reemerged in parts of Mexico, Central America, and the Caribbean. With recent detections north of the Panama isthmus, surveillance and awareness in the U.S. are increasingly vital.
3. What are the signs of an animal being infested?
Answer:
Watch for:
- Foul-smelling wounds with visible maggots
- Animals obsessively biting or licking wounds
- Lesions in navels, ears, branding or dehorning sites
- Unusual restlessness or lethargy
4. How can screwworm be identified?
Answer:
Larvae: Cream‑colored, screw‑shaped up to 17 mm long with protruding spines; confirmed by trained personnel.
Adult flies: Metallic blue green with three thoracic stripes and large orange eyes; similar to secondary species, but only C. hominivorax lays eggs on living tissue.
5. What should ranchers do if they suspect screwworm?
Answer:
- Isolate the affected animal immediately
- Contact your veterinarian, wildlife biologist, Texas Animal Health Commission (1‑800‑550‑8242), or USDA‐Veterinary Services (512‑383‑2400)
6. How is screwworm infestation treated?
Answer:
Treatment varies depending on timing:
- Preventive care: Keep wounds clean and monitor livestock
- Post‑infestation: Use topical larvicides (e.g.,
coumaphos, permethrin), thoroughly clean and debride wounds, manually
remove larvae
Always consult your veterinarian for guidance.
7. What long‑term control methods are available?
Answer:
Texas A&M recommends:
- Regular livestock inspections and biosecurity protocols
- Continued Sterile Insect Technique (SIT) releases of sterile males
- Active surveillance by agencies like USDA & APHIS
More resources:
- Download the updated New World screwworm fact sheet from Texas A&M AgriLife
https://agrilifeextension.tamu.edu/new-world-screwworm
- Access related links: USDA‑APHIS, Texas Animal Health Commission, Texas A&M Vet Diagnostic Lab.