Fly strike in cats, known medically as myiasis, is a condition where fly larvae (maggots) infest a cat’s skin or wounds and feed on its tissue. It happens when certain species of flies lay their eggs on or near a cat’s body, typically in areas that are moist, soiled, or wounded. The eggs hatch into larvae that burrow into the skin, causing progressive tissue destruction that can become life-threatening within days if left untreated.
How Fly Strike Happens
Flies are attracted to moisture, odor, and decaying organic matter. When a cat has an open wound, soiled fur, or skin irritation, female flies land on the affected area and deposit eggs directly on or near the skin. The eggs hatch into tiny larvae that begin feeding on dead tissue, wound secretions, and debris on the skin’s surface. As they grow, the larvae irritate and kill successive layers of skin, producing more fluid and decay that attracts even more flies.
This creates a self-reinforcing cycle. Once a strike is established, it spreads rapidly as new flies arrive to lay additional eggs. The larvae can tunnel through weakened skin into deeper tissue, creating cavities several centimeters wide. Advanced infestations may contain thousands of maggots. The primary fly species involved include green bottle flies and other blowflies, though the exact species varies by region. Fly strike occurs mostly in warm weather, when fly populations are highest.
Cats Most at Risk
Fly strike is not random. It overwhelmingly affects cats whose health or living situation prevents them from keeping themselves clean or getting prompt wound care. The most common risk factors include:
- Untreated wounds: Any open wound, whether from a car accident, dog bite, or surgery that wasn’t properly managed, is the single most common entry point. An untreated wound directly attracts egg-laying flies.
- Soiled fur: Cats whose fur is matted with urine or feces develop skin irritation and ulcers underneath. This is especially common in cats with incontinence, diarrhea, or mobility problems that prevent normal grooming.
- Obesity: Overweight cats sometimes cannot reach their hindquarters to groom. Cases have been documented in obese neutered cats that developed painful, foul-smelling ulcers on their thighs and tails from inability to self-clean.
- Immobility and old age: Cats that can’t move well, whether from fractures, arthritis, or advanced age, may develop pressure sores. These untreated sores attract flies.
- Feral and stray cats: Cats living without human care are especially vulnerable. Their fear of people means infestations can progress unchecked, and colony cats are difficult to monitor individually. Fatal cases have been reported in feral cat colonies.
- Newborn kittens: Fly strike has been documented in the umbilical area of neglected newborn kittens.
A common thread runs through nearly all cases: neglected health conditions. Cats receiving regular care rarely develop fly strike because wounds get treated, fur stays clean, and problems are caught early.
Signs to Watch For
Fly strike progresses through recognizable stages, and catching it early dramatically improves outcomes.
In the earliest phase, you may notice areas of matted, moist fur, sometimes with a patch of hair loss or raw-looking skin underneath. Visible fly eggs, which look like tiny white or yellowish clusters, may be present in the fur near wounds or soiled areas. A cat in the early stages of fly strike often becomes restless, licking or nibbling at the affected area repeatedly.
As the infestation advances, the signs become more obvious and more alarming. The skin develops round, punched-out holes that can merge into broad areas of tissue loss. Visible maggots appear in the wound, often embedded in exposed tissue. A distinct, pungent odor develops around the affected area. The cat may stop eating, become depressed, and stand or sit with its head down. At this stage, the damage is spreading rapidly beneath the skin surface, and what’s visible often underestimates the true extent of the problem.
Why Fly Strike Becomes Dangerous Quickly
What makes fly strike a genuine emergency is not just the tissue destruction itself but the body’s systemic response to it. As maggots feed and tunnel through tissue, they release ammonia and other waste products. Toxins from the damaged tissue are also absorbed through the raw, porous wounds directly into the bloodstream. This combination of ammonia poisoning and bacterial infection can trigger sepsis, a life-threatening whole-body inflammatory response.
A cat with advanced fly strike may become feverish, severely depressed, and unable to stand. Death can occur within just a few days, typically from sepsis or ammonia toxicity. Even mild cases cause rapid loss of body condition. The speed of progression is one of the most dangerous aspects: a small area of soiled fur in the morning can become a serious infestation by the next day in warm weather, because each new wave of tissue damage attracts more flies.
How Fly Strike Is Treated
Treatment starts with physically removing every maggot from the cat’s body. A veterinarian will clip the fur around the affected area, which is important both for removing larvae hiding in the hair and for revealing the full extent of the damage. Maggots embedded in tissue are carefully extracted, and all dead or dying tissue is cleaned away so healthy tissue can begin to heal.
For many cats, the visible wound turns out to be larger than expected once the fur is clipped. The larvae create tunnels and cavities beneath the skin that aren’t apparent from the surface. The vet will flush these pockets thoroughly. Depending on the severity, a cat may need intravenous fluids, pain management, and antibiotics to fight the bacterial infection that almost always accompanies a maggot infestation. Cats that are already showing signs of systemic illness, such as fever, collapse, or refusal to eat, need intensive supportive care.
Recovery depends heavily on how advanced the strike was when treatment began. Cats caught early, with damage limited to the skin surface, typically recover well once the larvae are removed and the wound is properly managed. Cats with deep tissue destruction, large wound areas, or signs of sepsis face a much more uncertain outcome. Some require repeated wound care over days or weeks as the tissue heals from the inside out.
Prevention
Fly strike is almost entirely preventable with basic care. Keeping wounds clean and properly bandaged removes the primary attractant for egg-laying flies. For cats with mobility issues, incontinence, or diarrhea, regular cleaning of the hindquarters and perineal area is essential, especially during warm months. Obese cats that can’t groom themselves need help keeping their coat clean until weight loss restores their flexibility.
Outdoor cats and cats with chronic health conditions need more frequent physical checks during fly season. Part the fur and inspect the skin around any wound, surgical site, or soiled area daily. Pay particular attention to areas the cat can’t easily reach. If you spot fly eggs in a cat’s fur, removing them immediately, before they hatch, prevents the infestation from ever starting.