Do Phorid Flies Kill Fire Ants?

Phorid flies are commonly present in decaying organic matter and moist places to get food and breed. However, some of these reproductive female phorid flies get attracted to ants belonging to the Solenopsis group and kill them by leaving their tiny parasitic eggs on their bodies.

Do Phorid Flies Kill Fire Ants? Phorid flies can kill fire ants as their parasitic species belonging to the genus Pseudacteon lay their eggs directly on the bodies of fire ants or close to their colonies. Also, they inject eggs into the thorax region, which grows into larvae and reaches the head region. These larvae decapitate the worker fire ants and pupate in their head. After that, the pupae feed on the dead ant and grow into adult flies.

They are considered an effective biocontrol agent against the invasive population of these damaging ants. They can help reduce the pest population to a great extent, but their effectiveness also relies on environmental conditions.

Why do phorid flies kill fire ants?

Phorid flies are parasitic organisms that look for a suitable host organism to lay their eggs because they get nutrition from the host, which leads to their death.

A few of them search for fire ants as they only lay eggs on this species and reach their colonies when their nests are disturbed.

They detect randomly moving fire ants in the environment when they feel the threat and release alarm pheromones to make their fellows alert about the possible danger.

The phorid flies detect these alarm pheromones due to their strong sense of smell and reach their swarms to lay eggs on their tiny bodies or inject them into the body.

These flies also get attracted to long foraging trails because they can detect pheromone secretions released by the foragers to make a trail.

So, they approach fire ants and target their bodies due to their parasitic nature, as they need a host to survive and get nutrition from their bodies.

The larvae cannot develop into adults if the eggs are not on the suitable host. In addition, the reason for attacking and killing are trail pheromones and the need for a host.

How do phorid flies kill fire ants?

The phorid flies are efficient parasitic organisms known as ant-decapitator flies for their killing behavior, as they target brain tissues and remove their heads to kill them.


This killing behavior starts with the egg-laying process by phorid flies when these tiny insects look for disturbed fire ant mounds and foraging trails in their surroundings.

The disturbed mounds and trails have a large number of ants and increase the likelihood of attacks due to easier identification.

They produce eggs close to their mounds so that they get adhered to randomly moving ants and find their way to the head after penetration.

In addition, some of these female flies also lay eggs directly on the host body that will hatch into larvae by entering their bodies.

One of the common mechanisms of parasitic species is to inject the larvae through a fine tube at the abdominal end. They sit on the thorax and inject eggs into the region between their legs.

Development of larvae

The eggs complete their early developmental stage in the thorax region and hatch into larvae. During development, they feed on body fluids and get nutrition from the fire ants.

The larvae also consume non-essential tissues and weaken their host slowly. An erratic behavior is observed in ants when infected with the phorid fly larvae.

In addition, the infected ant leaves the colony and moves away from the nest due to disruption in brain functioning.


The larvae of phorid flies enter the head region of the fire ants to kill them, as these parasitic creatures ultimately kill their host for nutrition.

They release specific enzymes in their head region to dissolve the brain tissues. They feed on the non-membranous tissues and live within the first segment of their bodies.

These enzymes break the tissues in the head, eventually leading to head removal and decapitation. They do not leave a broken head as the larvae complete the later developmental stage within it.

Pupation in decapitated fire ants

The decapitated heads of fire ants are a source of nutrition for the growing larvae, providing essential nutrients required for the pupation process.

They feed on the soft tissues and leave the hard structures like mandibles behind due to a lack of powerful chewing abilities. The pupating larvae also provide the other two body segments for food.

They do not leave the host body before turning into an adult phorid fly and move to the next host organism after reproducing.

Targeting next host

The mature phorid fly looks for another host species to lay eggs and is attracted to the nearby mounds if there is a swarm of worker ants outside it.

The adult fly takes almost 44 to 46 days to kill a fire ant and emerge as an adult that targets another population of host organisms.

These parasitic flies do not enter their mound for safety reasons and attack when they see a swarm of ants out of their closed nests. It provides an opportunity to inject eggs into their body.

So, the cycle of parasitic invasion continues in the next population, and the phorid flies keep killing the fire ants for their nutrition.

How do fire ants avoid phorid flies?

Fire ants are known for their deadly stings and killing potential, but phorid flies are the deadly predators of this species. They have a stinger to kill the predators and protect themselves.

However, these flies are adapted to lay eggs on the host organisms without getting bitten or stung by their host organism. These sit on the thorax region between their legs and inject tube.

They take only a few seconds to transfer eggs and fly away. In addition, the fire ants feel threatened after detecting phorid flies around them and try to avoid them by changing postures.

They try to avoid the sitting of flies by randomly moving and attaining odd postures.

Moreover, they ensure safety from attacks by pilling on each other, as this strategy helps reduce the body surface area available to these parasites for injecting eggs.

Furthermore, they hide in covered places and move within their nests after detecting the presence of parasitic or decapitating flies around them.

Which species of phorid flies is deadly for fire ants?

All species of phorid flies do not have a parasitic nature, and only a few species belonging to the genus Apocephalus attack fire ants and lay their eggs within their bodies.

In addition, most members of the genus Pseudacteon are known for their parasitizing behavior and break the heads of fire ants to feed and grow on them.

There is a parasitic relationship between fire ants and phorid flies of the Pseudacteon, which allows people to use them for biocontrol of the crop-damaging ants.

The colonies of red imported fire ants (Solenopsis invicta) are prone to parasitism by Pseudacteon tricuspis, while Pseudacteon litoralis injects eggs into the tropical fire ant species.

Moreover, the black imported fire ants are at risk of attacks from the Pseudacteon curvatus, so they try to defend themselves by stinging and hiding after detecting these parasitic flies.

So, all species of phorid flies are not parasitizing for them, and you can control the fire ant’s population by using the parasitizing species belonging to the Pseudacteon group.

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