How Maggots Go on Strike

Maggots Can Be a Nuisance or a Medical Treatment

Maggot (order Diptera)
Getty - Science Photo Library

If you've ever seen a dead animal in the middle of summer left lying out, chances are high that you have also seen wriggling, white maggots dispatching of the carcass. Maggots are the larvae of flies and feed voraciously off of dead, stinky, and decomposing material. An infestation of maggots on an animal is called a fly strike, or fly blown. The medical term for the animal infestation is myiasis.

Flies are most common in the warmer months. They can smell death and search out rotting flesh as a place to lay eggs. Within the day, the eggs develop into larvae that look like little white grub worms that need to feed.

Maggots as a Nuisance

Flies, including mosquitoes, are known to spread diseases, food poisoning, and dysentery. House flies, blow flies, and fruit flies, are also called “filth flies” because they feed off of garbage, dead meat or rotting food, and blood. 

If you have a pet that is recovering from a wound, and the pet is outdoors in one of the warmer months, it is not uncommon to see a swarm of flies circling the wound. Since fly larvae can appear quite fast, in some cases 8 to 12 hours, flies may try to deposit eggs. Vomit, diarrhea, skin infection (blood or pus), poor skin, and matted hair attract these pests. Maggots can grow and start to eat away tissue on your pet if these conditions are present.

The larvae only eat dead tissue, but they can be extremely painful and irritating to the pet. These conditions can appear and get worse within hours. Additionally, this condition can be fatal if left untreated. Contact your veterinarian immediately, rather than wait.

Treatment for Fly Strike

If an animal has fly strike, then treatment involves physical removal of the maggots, wound flushing and cleansing, removal of remaining dead tissue or fecal matter, clipping hair from the area to aid in drying of the affected areas, and often an antibiotic to speed healing.

The affected areas are usually tender and very painful. Sometimes veterinary sedation is necessary to fully cleanse the area and not damage the skin while cleaning the skin and coat.

It is important to find the cause of the maggot attraction. If there are no open wounds present, then is the animal vomiting? Does it have diarrhea? Very old, young, or compromised animals will be more at risk.

Maggots in Medical Situations

Even though flies have the reputation for being filthy, not all maggots are bad. Maggots are used medicinally to clean up (debride) wounds under very controlled conditions. Since antiquity, this method has been used as an effective way to clean a wound.

Today, maggot therapy is used in a controlled, sterile setting. A medical practitioner introduces live, disinfected maggots into non-healing skin or soft wounds of a human or animal. The maggots feed on the dead or necrotic tissue, leaving healthy tissues largely unharmed. Studies have shown that the maggots can kill bacteria that are present. This therapy is approved by the U.S. Food and Drug Administration, and the production and marketing of medical maggots are regulated by the federal government.

Nearly 4,000 therapists in 40 countries use maggot therapy; 700 in the U.S. alone.