Why do flies rub their hands together? Surprising answer

Have you ever observed a housefly (Musca domestica Linnaeus) or a blowfly (Calliphoridae) closely? You will find them rubbing their front set of limbs regularly as if they are getting ready for a big fight. You might have wondered why they do that.

Even though flies do not bite like mosquitoes but they create enough nuisance if even one of them enters our home. They will buzz around and keep on sitting on our bodies and food items.  

Flies serve a lot of purposes but they can be weird creatures. Let’s examine this in more detail.


Why do flies rub their hands together?

Many types of flies display this behavior of rubbing their front limbs together. Flies generally rub their hands together to clean them. It might seem funny to us as they always sit on garbage, poop, and leftover food; however, they need to get rid of the physical residues to ensure that their sensors work perfectly. They need these sensors for all the activities they perform like flying, finding food, going about their reproductive cycle which happens in four stages- egg, larva, pupa, and adult.

Hence having their sensors doing their work properly is a matter of life and death for a fly. This behavior should not cause any worry to humans.

Flies have sensory features all over their bodies

Another important fact that entomologists discovered through their research is that, flies can taste their food and can figure out whether tastes sweet or sour. They can actually use their sensors to taste their food even before eating it. They can taste their food using their wings and limbs. They have taste receptors all over their body and that’s why they can locate food from a great distance.

Human beings are not that evolved when it comes to their sensory nerves. If something good is cooking up in the kitchen, we can smell it sitting in another part of the house. However, unless the houses are closely stacked, we seldom get to know what is cooking in our neighbor’s apartment. Nonetheless, if there is a dead rat between the walls of our home, flies can sense it from a great distance and come to gather their food.

Some of the common types of flies-

There are more than 125,000 species of flies that are discovered by entomologists. It is believed that there are more than 1 million species of flies available on the surface of the earth. The entomologists are yet to discover them and document them. Let’s have a look at some of the common flies. All of these flies clean their legs by rubbing them together.

1.    Crane flies-

They belong to Family Tipulidae. They belong to the superfamily of Tipuloidea. They have long legs and look like mosquitoes. Colloquially they are known as ”mosquito hawks” due to their resemblance to mosquitoes. There are more than 15,000 species of crane flies in the world which are divided into 525 genera and subgenera.

Adult crane flies have a lifespan of 10 to 15 days. Normally the adult female contains mature eggs while emerging from the pupal stage and they are in search of males to copulate immediately after reaching the adult stage. Crane-fly eggs are black in color and the females often drop them in the air. The filament in the egg allows them to be anchored properly in a safe place.

2.    Tachinid Flies-

They belong to Family Tachinidae. There are more than 8,200 known species within this family with multiple subspecies. More than 1300 of species of this fly have been found in North America alone.

Most of the flies in this family are protelean parasitoids and they begin the initial phase (larval phase) of their lives as parasites. They are known to outbreak the larvae of beetles, moths, sawflies, stink bugs, and other insects, and the egg develops within the host eventually killing the host. By the time they convert into complete adults, they would have completely eaten up their hosts and emerged as adults.

Most of the Tachinid Flies complete their four stages of being between egg, larva, pupa, and adult within 3 to 4 weeks. There are some other species that spend a lot of time at the pupal stage and take about one complete year to complete their entire lifespan.

3.    Hover Flies-

They belong to Family Syrphidae. They are often known as flower flies as they hover around them and help in the process of pollination. They have the bright color of yellow and black and often camouflage well within the flowers. They look very similar to bees and wasps. When they are at the larval stage, they can survive on many types of food present in the garbage or heap of animal excreta. However, after becoming adults, they survive on flower nectar.

Almost 6000 species in this family divided in 200 genera have been discovered. They live for about a month which includes their life span as an egg, larva, and pupa.

Some of the benefits which flies cause to humankind

You might not like flies and think that they are dirty, despite the fact that they clean their legs by rubbing them together. Let’s take a look at why they are useful.

Gardeners welcome the maggots of hoverflies because they feed on aphids, thrips, and similar insects and safeguard the garden. Aphids are small bugs that suck the sap from the plants and spoil them. Hence hoverflies help in reducing the number of these harmful elements. The adults help in pollination.

Entomologists introduced some species of gall midges, fruit flies, and other families of flies to North America as work perfectly as weed biocontrol agents. They feed on the weeds and keep the produce safe.


Now since we have learnt a lot about different types of flies, their behavior we should act more responsibly. It is very important for us to ensure that they do not sit on our food items and contaminate them, on the other hand, they are extremely vital for our ecosystem. 

Given that flies like poop a lot, it can be quite dirty when they rub their hands.

During the summer vacations, you can ask your children to catch some flies and fill them in a glass jar. Then drop some small pieces of food and study their behavior. Who knows, they can grow up and become entomologists and study the behavior of a myriad of insects found on the surface of the earth. 




Tachinid Flies