Mouth Larvae: What to Know

Medically Reviewed by Poonam Sachdev on January 16, 2023
4 min read

Mouth larvae are parasites that hatch and live inside the oral cavities of human and animal hosts. These pests can cause a dangerous infection known as oral myiasis. This disorder rarely occurs in humans, but it can affect people living and traveling in developing countries. Certain conditions can make you more susceptible to oral myiasis. Here’s what you need to know about mouth larvae species, common causes of these creepy pests, and how to get rid of them.

The larvae of certain fly species can invade soft tissues inside the oral cavity, like gums and open wounds. These pests typically infect livestock and other vertebrate animals in tropical areas, but they can affect humans in rare cases. People can develop oral myiasis by eating larvae in their food. Flies can also enter the mouth and lay eggs in wounds. 

What do mouth larvae look like? This pest’s appearance varies depending on the type of larva. 

Screwworm fly larvae get their name from their screw-like appearance. One end of their body is blunt, while the other is pointy. They have cylindrical, creamy white bodies that darken to reddish-pink as the larvae mature. 

Flesh fly larvae have long, white bodies with narrow heads. They can grow to 9 to 13 millimeters long in their final larval phase. The bodies of flesh fly larvae grow darker as they progress through pupal development. 

Human botfly larvae are commonly known as white maggots. Their appearance evolves as the larvae move through three stages. The larvae begin as small, worm-like creatures with one narrow end and one bulbous end. During the second stage, the larvae’s bodies grow in size and narrow into a bottle shape. In the third stage, the larvae’s bodies become cylindrical. The botfly mouth larvae’s bodies are ringed with dark spines at each phase. 

Horse botfly larvae typically burrow into the mouths of horses. These pests have off-white bodies with narrow ends and rings of spines. They measure up to ½ inch long. 

What do mouth larvae eat? These parasites feed on the dead or living tissue of their hosts. They can also eat bodily fluids and ingested food that gets caught in the mouth. 

As mouth larvae feed on their hosts, they produce toxins and attract bacteria that release compounds that cause the host’s tissue to decay. This makes it easier for the larvae to burrow inside and eat. 

What is the life cycle of mouth larvae? Each species of mouth larvae has a unique life cycle, but these pests typically have similar life stages. 

The adult human botfly glues its eggs to the bodies of blood-sucking arthropods like mosquitoes. When the vector drinks blood from a bird or mammal, the botfly larvae penetrate the host’s tissue. The immature botflies find a suitable cavity in the host’s body and feed on their tissue for five to 10 weeks. 

After reaching maturity, the larvae emerge from the host and pupate in the ground. They mature into adult flies in two to three weeks.

Experts estimate that over 80 species of flies can cause oral myiasis. Here are four mouth larvae species discovered in humans: 

Screwworm fly (Cochiliomyia hominivorax). This species lives in tropical and semitropical regions of the Western Hemisphere, including the Caribbean and some parts of South America. The female screwworm fly lays eggs on mucous membranes or wounds, and the larvae burrow into the tissue after hatching. This pest commonly affects livestock and pets and can cause death if wounds are left untreated. 

Human botfly (Dermatobia hominis). The human botfly lives in Central and South America. Adult human botflies resemble bumblebees and lay larvae in mammals’ skin, mouth, and other tissues. 

Flesh fly (Sacrophagidae). This pest has a vast range, occurring in areas like Greenland, Central America, and North America. These flies can infect living hosts and feed on human and animal remains.

Mouth larvae live in tropical and subtropical countries with humid, warm environments, like India and South America. They often occur in impoverished rural areas with poor living conditions. 

People in the Northern Hemisphere and Europe rarely have oral myiasis. Most Americans who develop this condition get the parasites while traveling in Africa and South America.

Symptoms of mouth larvae include: 

  • Destruction of oral tissues
  • Lesions
  • Mild to acute pain
  • Necrotic gums 
  • Pulsating extraction wounds 
  • Oozing lesions

Seek medical treatment immediately if you suspect you have mouth larvae.

Mouth larvae typically infect people with conditions that affect their ability to close their mouths. Oral myiasis has been linked to: 

Poor oral hygiene and trapped food debris can make your mouth an attractive place for flies to lay eggs.

Oral myiasis can cause many adverse health effects, including: 

  • Extreme pain
  • Inflammation in the mouth
  • Larvae rupture
  • Permanent tissue damage

Severe infestations of mouth larvae can be fatal without appropriate treatment.

Health care professionals can treat mouth larvae by topically applying chloroform, mercuric chloride, mineral oil, or turpentine. These substances suffocate the larvae and force them to emerge from mouth tissues for oxygen. 

After this application, a doctor typically extracts the mouth larvae surgically using clinical pincers or hemostats. Lidocaine is sometimes injected into cysts to push larvae to the surface. 

Patients should receive antibiotics to treat secondary bacterial infections caused by mouth larvae and multivitamins to supplement their diet.

Treatment for oral myiasis requires surgical extraction of the invading pests. Patients typically recover fully after mouth larva removal. 
Strategies to prevent mouth larvae include: 

  • Eliminating local fly populations
  • Improving community hygiene
  • Maintaining personal cleanliness
  • Monitoring people with mental and physical disabilities for signs of oral myiasis 
  • Practicing good oral hygiene 

Travelers should exercise extra care when visiting areas known for myiasis. Applying insect repellant, wearing long sleeves and pants, and using mosquito nets can help protect you from mouth larvae.