Robber flies are named after their ability to rob insects of their lives in mid-air! But which insects do they attack? What do robber flies eat? Let’s figure it out.
There are around 7,000 species of robber flies in the world, and nearly 1,000 of them are native to North America.
Robber flies are one of the most fascinating creatures in the insect kingdom. They are known to be excellent hunters.
These little bugs can catch prey in mid-air, pouncing on unsuspecting bugs that happen to fly past them. In this article, we will talk about what robber flies eat and why this might be beneficial to humans.
What Do They Eat?
Robber flies (order Diptera, family Asilidae) are excellent hunters and usually prey on smaller insects, but they are also seen attacking insects bigger than themselves. In fact, adult robber flies eat anything that they can hunt.
Robber flies can also be cannibalistic and larger ones are often seen hunting and eating smaller robber flies. Let us look closely at what they eat.
Adults
Adult robber flies mostly hunt smaller insects like flies, ants, and more. But they will not hesitate to hunt down bigger insects like honey bees, dragonflies, and butterflies if they get a chance.
The insects they usually hunt are beetles, flies, moths, wasps, ants, crickets, grasshoppers, lacewings, and mayflies.
The adults will also pursue other smaller species of robber flies. These flies will also attack humans in the act of defense if they try to threaten them or mishandle them.
Larvae
There is a limited amount of data about what the robber fly larva eats.
One of the prime reasons behind this is that these creatures live in places like decaying wooden logs or soil, which are hard to access.
The only known info is that these larvae eat prey like grasshopper eggs and beetle larvae.
How Do They Hunt?
Robber flies live up to their other name – assassin flies. They are great hunters who often stalk innocent insects passing by an area from a vantage point.
Once the time is right, they pounce on the prey and inject them with their saliva using their long proboscis (needle-like mouthpart insects use to suck things).
The saliva contains neurotoxic enzymes that paralyze the target. It also contains proteolytic enzymes and other digestive enzymes that liquefy the inside organs of the hunt.
One fascinating thing about their hunting behavior is that they usually carry the prey back to their territory before consuming it.
Once they enter their zone, they rest on the branch to feast on their meal.
In the case of smaller prey, it can take around 5-15 minutes to finish off the meal; for the heavier targets, it can take up to an hour.
Adaptations That Help Them Hunt and Eat
These agile hunters have evolved several features that help them to hunt efficiently.
They are equipped with strong legs, spiky bristles on their body, a long and sharp proboscis, and large compound eyes.
Let us look at these features in detail below:
Proboscis
The proboscis is one of the primary weapons that a robber fly uses to hunt. It is a dagger-like beak that acts both as a weapon for impaling and as a straw for eating their food.
The flies use the proboscis to inject saliva into the prey, which paralyzes them. Once the target is paralyzed, they inject digestive enzymes that liquify the internal tissues of the hunt.
These digestive enzymes do not damage the outer skeleton of the body, but make it easy for them to suck out the juices.
Once the flies carry the kill to their territory, they use the proboscis to suck the liquid and complete their meal.
Bristles Around The Mouth
If you look closely, you will notice a good bunch of bristle-like hair on their faces (known as mystax) between the eyes and mouth.
Since they are active hunters and are seen hunting larger prey, these bristles protect the flies from receiving facial damage from the struggling insects when they inject the saliva and impale the prey.
Several Eyes
Here is one of the most intriguing facts about robber flies, they have more than two eyes. Yes, you read it right!
Although you may only notice a large pair of eyes on these flies, they do have three simple eyes located on the top of their head in a wedged area between the two big eyes.
These extra eyes help them to find their prey better and to detect danger in the area that normal eyes can’t.
Strong Legs
Since these insects often carry their prey back to the territory to eat them, they need a strong pair of legs to help move the weight of heavier insects like dragonflies and bees.
The legs of robber flies are spiny but tough, and they help them carry weights much larger than themselves.
Lifecycle
The female robber flies lay eggs in areas and plants that are close to the ground or in some corner of a wooden log.
When these eggs hatch, the larva comes out and lives and grows in soil or in decaying wood.
These larvae are also predatory in nature and are often seen eating eggs of pest insects like grasshoppers and beetles.
During winters, robber flies overwinter in the soil as larvae or by transforming into pupae. They come only out of the soil once the temperatures are higher, and they can find ample food for themselves.
Are They Beneficial?
These flies will consume any insect that they can kill, which means they will remove pests and other beneficial insects like white grubs from your garden.
Also, while they are capable of inflicting pain through their bites, they are great hunters of pests like grasshoppers, beetles, and more.
These flies are like a mixed blessing to the farmers, as they are capable of killing beneficial insects but also removing almost all unwanted pests from the garden.
How To Invite Them To Your Garden
Robber flies are omnivorous creatures. Although the central part of their diet consists of insects, they drink nectar from the flowers.
So if you want to invite these beneficial insects to your garden, try planting more and more flowers. Both smaller and larger robber flies will be attracted to flowers for the nectar.
Frequently Asked Questions
Can robber flies bite humans?
Yes, robber flies are capable of biting humans. Due to the digestive enzymes and venom present in their saliva, they are capable of delivering painful bites, so humans must be careful around them. These flies won’t attack a human until they are threatened or manhandled.
What are robber flies attracted to?
Robber flies are highly attracted to areas that get plenty of sunlight and are full of flowering plants. Such sites are usually full of robber fly prey.
They are also great sources to obtain nectar that supplements their majorly carnivorous diet. So if you want to invite these flies to the garden, make sure it is filled with good flowers and plants.
Do robber flies eat mosquitoes?
Robber flies are superlative hunters and are known to consume any insect that they can hunt.
The list of prey includes everyone starting from mosquitos, flies, beetles, butterflies, moths, ants, wasps, bees, and more.
Larger robber flies are also known to consume their smaller cousins!.
Are robber flies aggressive?
Robber flies are aggressive in hunting and are known even to kill and consume insects that are bigger than them.
They are usually not aggressive towards humans until they are threatened and mishandled. One should not approach these flies recklessly as they are capable of providing extremely painful bites.
Wrap Up
Robber flies are fascinating creatures with unique bodies and a thirst for the hunt like no other. These silent assassins of nature can quickly wipe out an entire garden full of bugs.
Knowing about these creatures will help you understand them and handle them better. We hope this article provides all the necessary information about these flies.
Thank you for taking the time to read this article.
s
J
.
