New World Screwworm Overview

New World screwworm (Cochliomyia hominivorax) is a foreign animal disease and a serious threat to wildlife, livestock, pets and people.

The fly’s larvae infest open wounds, where they feed on living tissue.

This pest was eradicated from the U.S. decades ago, but recent detections in Mexico and south Texas pose a risk of northward spread.

New Mexico needs your help to prevent the spread of this disease.

pdf - Be On The Lookout for New World Screwworm
Closeup of an adult New World screwworm fly

Photo by USDA

Precautions

As you spend time in the outdoors this season, please check harvested game and live animals you encounter for:

• Larvae (maggots) on alive or very recently deceased animals. Unlike other maggots, New World screwworm (NWS) larvae feed on living tissue.

• Maggots deep in tissue with foul odor. Common sites are wounds or body openings like the nose or genitalia.

In the event that you see suspected NWS:

  1. Take a GPS location.
  2. If it is a game animal, contact the New Mexico Department of Wildlife as soon as possible at 888-248-6866 during regular business hours. After hours or on weekends, please call your local conservation officers.
  3. If it is a livestock animal, contact the New Mexico Livestock Board at 505-841-6161 as soon as possible.
  4. Do not eat, handle or transport the animal.
  5. Take pictures of the wound, larvae or affected animal if possible.
  6. If you can, collect a sample safely. Using gloves or tweezers, place several larvae into a sealed container (small jar or plastic vial) with 70% alcohol. Label with date, GPS location, species and your contact info. Report and submit immediately to New Mexico Department of Wildlife or the New Mexico Livestock Board.

Your reports are critical for early detection and rapid response.

Quick action could protect wildlife and livestock across the state.

*** Please remember that even minor mishandling of game meat can cause non-NWS maggots to develop in muscle tissue. New World screwworms will only be found on alive or very recently dead animals.***