What does it look like?

Image gallery, field signs, and lifecycle visuals.

43 official imagesGraphic contentUSDA APHIS gallery COPEG photos

Adult New World screwworm fly with orange eyes and metallic body — **Adult fly**
Orange eyes, metallic blue-green body, dark back stripes.
Photo by USDASource

New World screwworm fly and eggs — **Fly and eggs**
Eggs are laid on wounds or moist body openings.
Photo by USDASource

New World screwworm fly with egg mass on wound — **Egg mass on wound**
Even small wounds can attract egg-laying flies.
Photo by USDASource

Mature New World screwworm larvae — **Mature larvae**
Larvae burrow into living tissue after hatching.
Photo by COPEGSource

Closeup of New World screwworm larva showing mouth hooks — **Larva mouth hooks**
Mouth hooks tear tissue and can deepen wounds.
Photo by USDASource

Closeup of a New World screwworm larva — **Larva closeup**
Close larval view for shape and body detail.
Photo by USDASource

New World screwworm larva reference image — **Larva detail**
Another close reference for larval appearance.
Photo by USDASource

Two New World screwworm larvae — **Two larvae**
Side-by-side larvae reference.
Photo by USDASource

Closeup of three New World screwworm larvae — **Three larvae**
Larvae grouped for size and body comparison.
Photo by Sohath Yusseff-Vanegas, USDA Agricultural Research ServiceSource

Closeup image of three New World screwworm larvae — **Larvae comparison**
Second grouped larvae reference.
Photo by Sohath Yusseff-Vanegas, USDA Agricultural Research ServiceSource

New World screwworm pupae — **Pupae**
Larvae drop from wounds and pupate in soil.
Photo by COPEGSource

Adult New World screwworm fly — **Adult fly vertical**
Another adult fly angle.
Photo by USDASource

Ear-tag wound infested with New World screwworm — **Ear-tag wound**
Tag sites and small wounds deserve close checks.
Photo by Dr. Feliciano Bravo, COPEGSource

Newborn animal navel infested with New World screwworm — **Newborn navel**
Navels on newborn animals are high-risk sites.
Photo by Sohath Yusseff-Vanegas, USDA Agricultural Research ServiceSource

Deer infested with New World screwworm — **Deer infestation**
Wildlife can carry visible infestations too.
Photo by USDASource

Deer with New World screwworm infestation — **Deer wound**
Second wildlife reference from APHIS.
Photo by USDASource

Inspecting larvae removed from an infested horse — **Horse larvae check**
Larvae removed from an infested horse.
Photo by Dr. Feliciano Bravo, COPEGSource

New World screwworm infestation in a horse leg — **Horse leg**
Leg wounds can become infestation sites.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat leg wound with New World screwworm infestation — **Goat leg wound**
Leg wound reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Closeup of goat wound with New World screwworm infestation — **Goat wound**
Close view of an infested wound.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat wound with New World screwworm infestation — **Goat wound closeup**
Another close wound reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat head wound from New World screwworm infestation — **Goat head wound**
Head wounds need prompt attention.
Photo by Dr. Feliciano Bravo, COPEGSource

Pig mouth infested with New World screwworm — **Pig mouth**
Body openings can be affected.
Photo by Dr. Feliciano Bravo, COPEGSource

Chicken infested with New World screwworm — **Chicken infestation**
Birds can be affected in some cases.
Photo by Dr. Feliciano Bravo, COPEGSource

Closeup of chicken infested with New World screwworm — **Chicken closeup**
Close bird reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Dog with New World screwworm infestation near the eye — **Dog eye area**
Pets can need urgent veterinary care.
Photo by Dr. Feliciano Bravo, COPEGSource

Severe New World screwworm infestation on a dog's neck — **Dog neck**
Severe neck wound reference.
Photo by Winthorpe Marsden, Jamaican Ministry of AgricultureSource

Dog paw with New World screwworm myiasis — **Dog paw**
Feet and paws can hide wounds.
Photo by USDASource

New World screwworm fly, larva, and egg in a wound — **Fly, eggs, and larvae**
Eggs, larvae, and fly on a wound.
Photo by Samantha Gibbs, U.S. Fish and Wildlife ServiceSource

New World screwworm flies attracted to an animal wound — **Flies on wound**
Open wounds attract adult flies.
Photo by USDASource

Tunneling wound from New World screwworm myiasis — **Tunneling wound**
Deep wound pattern to treat as urgent.
Photo by USDASource

Animal hoof infested with New World screwworm — **Hoof wound**
Hooves and lower legs can hide damage.
Photo by USDASource

Removing New World screwworm larvae from an infested animal — **Removing larvae**
Removal and treatment belong with professionals.
Photo by USDASource

Cow treated for New World screwworm infestation — **Cow treated**
Treatment follow-up reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat wound being treated for New World screwworm infestation — **Goat treatment**
Treatment view on a goat wound.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat head wound being treated for New World screwworm infestation — **Goat head treatment**
Treatment near the head.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat wound treated for New World screwworm infestation — **Goat wound treatment**
Treated wound reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Closeup of treated goat wound after New World screwworm infestation — **Goat treatment closeup**
Close treatment reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat wound treatment for New World screwworm infestation — **Goat treatment view**
Treatment view from APHIS.
Photo by Dr. Feliciano Bravo, COPEGSource

Detailed goat wound treatment for New World screwworm infestation — **Goat treatment detail**
Another treatment detail.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat treatment follow-up for New World screwworm infestation — **Goat treatment follow-up**
Follow-up view from APHIS.
Photo by Dr. Feliciano Bravo, COPEGSource

Goat wound follow-up after New World screwworm treatment — **Goat wound follow-up**
Additional treatment follow-up.
Photo by Dr. Feliciano Bravo, COPEGSource

Dog treated for New World screwworm infestation — **Dog treated**
Pet treatment reference.
Photo by Dr. Feliciano Bravo, COPEGSource

Life Cycle

Screwworm larvae feed on living tissue.

The animation shows the stages from adult fly to eggs, larvae, pupae, and the next generation.

Field Cues

Signs that deserve a closer look or a call.

If a wound looks suspicious, contact a veterinarian, state animal health official, or USDA.

Wound ChangeWet, widening, painful, or foul-smelling.

Drainage

Expanding edge

Odor

Actual reference photo

Draining or enlarging wounds

Treat a wound that is getting wider, deeper, wetter, swollen, bloody, painful, or foul-smelling as an urgent second-look case.

Drainage or bleeding
Wound edges expanding
Foul odor with swelling or pain

USDA APHIS owner guidance

Odor CuePair smell with visible wound changes.

Putrid smell

Drainage

Swelling or pain

Field-cue illustration

Foul odor or decay smell

Smell alone does not diagnose screwworm, but a putrid odor with drainage, swelling, pain, or visible larvae should raise urgency.

Putrid or decaying smell
Bloody discharge
Odor plus swelling or pain

CDC clinical overview

Eggs Or LarvaeLook for movement in living tissue.

Egg massLarvaeMovementMoist wound

Visible larvae in a wound should trigger a call to a veterinarian or animal-health official.

Actual reference photo

Maggots or egg masses

Look for eggs or larvae in wounds and around moist tissue. Maggots feeding in living tissue are the concern that needs immediate reporting.

Creamy egg masses near wound edges
Visible larvae or maggots
Movement inside living tissue

USDA APHIS field brochure

High-Risk SitesCheck moist openings and newborn navels.

NoseEarsGenital areaNewborn navel

Lesions, drainage, odor, or movement near these sites should trigger a call.

Body-site illustration

Lesions in body openings

Check nose, ears, genital areas, the umbilical area of newborn animals, and other moist openings where lesions can be easy to miss.

Nose, ears, or genital area
Umbilical area on newborns
Lesion, drainage, or odor near an opening

USDA APHIS owner guidance

Behavior ChangeLook at the animal and the wound together.

Discomfort plus a suspicious wound should move the case up the urgency list.

Behavior cue illustration

Signs of discomfort

Behavior does not diagnose screwworm, but discomfort plus a suspicious wound should trigger a closer inspection and a call for help.

Irritated or restless behavior
Depression or not eating
Isolation from other animals or people

USDA APHIS owner guidance