Flystrike starts as small clusters of white or yellowish eggs on soiled fur, wool, or skin near a wound. Within hours, those eggs hatch into tiny maggots that burrow into the skin, creating an expanding area of raw, weeping tissue that smells foul and can kill an animal surprisingly fast. Knowing what each stage looks like gives you the best chance of catching it early.
What the Earliest Stage Looks Like
Before any visible damage appears, blowflies lay small, rice-grain-sized eggs in clusters on damp or dirty areas of an animal’s body. The eggs are pale white to cream-colored and are usually tucked into matted fur, soiled wool, or the edges of an existing wound. They’re easy to miss because they blend in with bedding or light-colored coats. At warm temperatures, these eggs can hatch into first-stage larvae in as little as 9 to 12 hours, so this window is brief.
The most common places to find eggs are around the rear end (where fur or wool gets soaked with urine or feces), around open wounds, and in any area where the coat has become damp and matted. In sheep, the breech is the classic site, but strikes can also occur around the horns of rams, the prepuce, and anywhere footrot touches the fleece. In rabbits and chickens, the area around the tail and vent is most vulnerable.
What Active Flystrike Looks Like
Once eggs hatch, the initial skin lesion often looks like an insect bite or a small boil with a central opening. That opening typically oozes a thin, blood-tinged fluid. Sometimes you can see the tip of a larva poking through. At this point, the surrounding skin may appear red and irritated, and the fur or feathers around it will be damp and discolored.
As the maggots grow, the picture changes quickly. You’ll see small, wriggling, cream-colored larvae in a moist, reddened wound. The affected area gives off a strong, unmistakable rotting smell. The tissue around the larvae becomes soft and eroded as they feed, and the wound edges spread outward. Discharge turns from blood-tinged to thick and yellowish as secondary bacterial infection sets in. In animals with thick coats, you may notice a dark, moist patch on the surface of the wool or fur before you see the maggots underneath, so parting the coat and inspecting the skin directly is essential.
In advanced cases, the maggots burrow deeper. The wound becomes a crater of dead, blackened tissue with visible holes and cavities where larvae have tunneled in. Skin destruction can spread rapidly over hours, exposing raw muscle or deeper tissue. The smell at this stage is intense enough to notice from several feet away.
Behavioral Signs Before You See the Wound
Animals often show distress before you spot the maggots, especially if the strike is in a hard-to-see location. Rabbits with flystrike typically become quiet and lethargic, stop eating and drinking, and adopt a hunched posture. One distinctive behavior is digging into corners, which is their attempt to relieve the pain and irritation. They may also stamp their hind feet or constantly shift position.
Sheep will bite at the affected area, wag their tails persistently, and separate from the flock. Chickens may become withdrawn, fluff their feathers, and sit in one spot. Any sudden change in behavior during warm, humid weather should prompt a physical check of the rear end and any existing wounds.
How Quickly It Gets Dangerous
Flystrike can progress from egg-laying to life-threatening tissue destruction in 24 to 48 hours in warm conditions. The speed is temperature-dependent: hotter weather accelerates every stage of the blowfly life cycle. Warm, moist conditions are ideal for blowfly breeding, and a synchronized wave of flies often emerges in early spring once soil temperatures rise above 15°C (59°F).
As maggots feed and grow, they release toxins into the bloodstream. This causes a condition called toxemia, where the animal essentially goes into toxic shock. Signs of this systemic stage include collapse, cold extremities, pale or purple-tinged gums (visible in rabbits and reptiles), and unresponsiveness. Hemorrhages may appear under the skin. Once an animal reaches this stage, survival rates drop dramatically even with aggressive treatment.
What Veterinary Treatment Involves
If you find maggots on your animal, getting to a vet quickly is the single most important factor. Treatment centers on physically removing every maggot from the wound. This is painstaking work because larvae hide in tunnels and cavities within the damaged tissue, and any dead maggots left behind can trigger a serious secondary infection. Vets sometimes use oil-based solutions to immobilize the larvae before extracting them one by one, taking care not to rupture them in the process.
After removal, the wound is flushed extensively with antiseptic solution and dead tissue is trimmed away. The wound then needs daily dressing changes as it heals. Antibiotics are often given to control bacterial infection. The animal also needs supportive care: a warm, quiet space, easy access to food and water, and protection from further fly exposure while recovering. Recovery time depends on how much tissue was destroyed, ranging from days for a mild case to weeks for extensive wounds.
Reducing the Risk
The most effective prevention is keeping your animal clean and dry, particularly around the rear end. For rabbits, this means checking the area under their tail at least twice daily in warm weather, keeping hutches clean, and managing any conditions like obesity or dental problems that prevent them from grooming properly. For sheep, keeping the breech area free of fecal soiling and treating any skin wounds or footrot promptly removes the conditions that attract flies in the first place.
Chemical preventatives are widely used in livestock. The most common options include insect growth regulators that prevent larvae from developing on the animal. In Australian sheep farming, the two most popular products provide protection ranging from about 8 to 29 weeks depending on the specific formulation, though emerging resistance in blowfly populations has shortened those protection windows significantly in some regions. One study found that protection periods dropped to less than half of the labeled claims against resistant fly strains. This means chemical prevention alone isn’t enough; regular physical checks remain essential even when preventative treatments are in place.
For pet rabbits and backyard poultry, fly screens on enclosures, prompt removal of soiled bedding, and sticky fly traps around housing all reduce fly contact. During peak fly season (late spring through early autumn in most climates), daily inspections of vulnerable areas take only a few seconds and can catch a strike before it becomes an emergency.