Do-it-yourself flycatcher at home. How to make a fly trap at home. Do-it-yourself sticky fly tape

Flies are the most common and annoying insects that live side by side with humans. Getting rid of them sometimes becomes a real problem, and often you can not do without special tools, one of which is a fly trap. Of course, you can buy it, but it's easy to do it yourself.

Is it necessary to fight flies and why

These insects not only bother with their buzzing - their neighborhood is much more dangerous than it might seem. Flies are carriers of pathogens of various diseases - intestinal infections, eye diseases, tuberculosis. Also, on their paws, they often lay eggs of worms on the products they sit on. That is why the fight against them indoors is an important task for ensuring sanitation and maintaining human health.

The main types of traps, their effectiveness, advantages and disadvantages

One of the most versatile means for exterminating unwanted neighbors is a fly trap. With your own hands, you can make many options for its execution from improvised materials.

The simplest is from a plastic bottle with sweet bait (it also helps against wasps)

Plastic bottle trap

Ease of manufacture is its main advantage. This requires one empty plastic bottle with a volume of 1.5–2 liters.

In order to make a trap, you need:

The disadvantage of this flycatcher is that a small part of the insects can leave the trap, and you also need to constantly change the bait with the caught flies. Fermented bait can smell bad.

Glass jar option

The principle of catching a flycatcher from glass jar the same as in the bottle version.

It is made as follows:

1. In a jar with a volume of 0.5 to 3 liters, put fruit or pour sugar-containing liquid.
2. Insert the funnel for pouring liquid with a narrow end into the neck of the jar and secure it with tape.
3. Place the trap where you want to catch the insects.

The effectiveness of this flytrap is comparable to that of a bottle trap. Periodically it is necessary to change the bait and remove the caught insects.

Analogue from any container and cling film

For the manufacture of this flytrap is used Plastic container any shape - round or square. The trap is done like this:

The principle of operation of the trap is the same as the previous ones. Some flies may leave the trap, and its effectiveness will depend on how attractive the bait is to the insects.

Household adhesive tape

The advantage of this trap is that the flies do not need to get inside closed space, which scares some insects, so its effectiveness is higher than the previous options presented. You can make it yourself as follows:

1. Mix 2 parts pine resin with 1 part linseed oil and a small amount of sugar syrup.
2. Cut strips of plastic film 3-4 cm wide.
3. Apply the prepared adhesive mixture with a brush to the tapes.
4. Hang traps in the room where you want to destroy insects.

One of the disadvantages of adhesive tapes is their poor aesthetics.

"People's" insect repellers - plastic bags with water

A simple, albeit somewhat controversial fly protection solution. In order to make such a repeller, you need the following:

The inventor claims that this device can be compared in efficiency with mosquito nets, but this is a rather controversial issue.

Velcro pendant from CD

To make this trap, you need the following:

The disadvantage of this flycatcher is that it is periodically necessary to clean the disk of flies, lubricate it with an adhesive base and send it to the freezer.

How to make an electric fly trap

For the manufacture of this category of traps, you must have electrical skills. In addition, you need to have a list necessary materials, which will not be in every home.

Electric landing net: manufacturing instructions

The principle of operation of this electric trap is based on the belief that flies will fly to the light of the lamp, however, even professional flytraps using lamps to lure turn out to be more effective against mosquitoes, while flies, according to user reviews, often bypass the trap.

To make this flytrap, you will need the following materials and tools:

• Pliers;
• Screwdriver;
• Scissors for metal;
• A small electric motor from the player;
• Ordinary light bulb with a cartridge;
• Pair cans with different diameters;
• Aluminum or tin strip 20x100 mm in size;
• 2 washers made of plastic;
• Epoxy resin with a thickener;
• metal strips;
• Screws and bolts M4;
• Round base made of wood;
• Nylon stocking;
• rubber ring;
• The power source is a pair of AA batteries.

As you can see, this device is not the latest invention, but also Soviet

You need to make a trap as follows:

The disadvantage of this trap is the complexity of its manufacture and low efficiency for catching flies in comparison with other traps.

Electric shock flytrap

To lure insects in this flycatcher, the light of a lamp is also used, which in practice is far from always effective against flies. To make it, you will need the following materials:

• Bulb housekeeper;
• Ordinary finger battery or "Krona".
• high voltage module.
• aluminum wire.

The electric shock is made as follows:

1. Disassemble the housekeeper and drill two holes opposite each other on the sides of the plastic base.
2. Insert an aluminum wire into each hole and wrap it around the body.
3. Connect one of the wires that come out of the neon lamp with the end of the wire.
4. Connect the remaining two contacts of the neon bulb to the high-voltage module.
5. Connect the high voltage module to the batteries through the switch button.
6. Fix the module and batteries on the bulb body with electrical tape.
7. Turn on the device - insects attracted by light when touched aluminum wire will be amazed electric shock.

The disadvantage of this trap is that it is also unsafe for a person if, inadvertently, touching a bare wire, it also has low efficiency compared to traps that use sugar-containing substances or pheromones as bait.

Plants that are eaten for flies

Predatory plants are quite an exotic way to catch flies, but they can still help get rid of a few annoying insects. Most often in room conditions the following species are grown:

Industrial traps for rooms and garden

There are also industrial versions of fly traps.

• Aeroxon. glue trap, which composition of a bait includes environmentally friendly ingredients.
  
• DELUX AKL-31. A trap whose principle is based on attracting insects with ultraviolet light. Flies flying up to her are struck by an electric current. Although the manufacturer positions it as a universal device against mosquitoes, mosquitoes and flies, the latter rarely become trophies of this trap.
  
• FC001. A mechanical trap, inside which it is necessary to insert a tablet with an attracting substance, which includes synthesized (Z) -9-Tricosin - a pheromone secreted by flies to attract individuals of the opposite sex during mating. The action of the tablet is very long - 2-3 tablets may be enough for one season.
  

Professional traps vary in cost, and they are also superior in convenience and efficiency to home-made options.

The cutest option is the Australian bollard trap

This trap can be used outdoors - for example, near the dining table under a canopy in the country, as its trapping capacity is quite high, and maintenance operations are extremely rare.

Outwardly, the flycatcher looks like a bedside table from wooden frame with small legs, covered on all sides with a fine mesh, under the bottom of which a saucer with a sugar-containing liquid is placed. The secret of catching flies lies in the pyramidal shape of the mesh bottom of the trap, in which there is a hole. As a rule, having satiated, the flies fly up, not paying attention to the transparent mesh.. As a result, insects enter the flycatcher through a hole in the bottom.

For the manufacture will require the following materials:

The process of making a flycatcher is as follows:

1. From wooden planks, assemble the frame in such a way that the whole structure stands on legs about 5 cm high, attach the upper part to the canopies and equip it with a hook.
   
2. Cover all sides, except the bottom, with a metal mesh.
3. To make a pyramidal bottom of the trap from the mesh, connecting the seams of the mesh with metal screws, you can also use brackets for a furniture stapler for this.
4. At the top of the pyramidal bottom, cut a hole 2 cm in diameter so that the flies enter the trap through it.
5. Lubricate all joints between the mesh and wooden planks with sealant.
   
6. Place the trap in the required place, after placing a saucer under it with an alluring liquid - sugar syrup or jam. Industrial fly attractants can also be used.
   

The advantage of this flytrap is that maintenance is rare, because sometimes it is only necessary to release the flies from the trap, and also to replace the attracting liquid in the saucer.

Prevention of the appearance of flies in the house

In order for the flies not to annoy, it is necessary to constantly adhere to preventive measures that prevent their appearance:

By following these preventive measures, you can significantly reduce the number of annoying insects. It is also recommended to install traps even in rooms where the number of insects is negligible.

With the advent of August - the time of ripening of most fruits, unwanted insects such as fruit flies appear in the house. Inconspicuous fruit flies begin to attack all fruits and vegetables, as soon as they lie down for a while. How to get rid of them without harming yourself, you can find out by reading this article.

Where do fruit flies come from in the house?

These insects are the eternal companions of man, they feed on spoiled, rotten foods, which people have in abundance. Only with mass harvesting, constant stay in the house of vegetables and fruits, there are a lot of fruit flies. They multiply intensively and lay eggs on food. Since the eggs and larvae are very small, a person cannot notice them on the fruit. Leaving the purchased watermelon or apples with pears, you can see fruit flies the next day, actively interfering with the usual way of life.

Ways to get rid

If you can’t remove the cause of their appearance, as well as hide all the products, then you can use the following tools:

1. A trap from a can. Place the bait on the bottom (a piece of fruit or juice, compote). Make a paper funnel with a small hole. Glue the joint with adhesive tape. Place with the pointed end of the funnel down. Leave overnight. In the morning, cover and throw the “harvest” out into the street.

2. Plastic cup trap . Take a glass and put the bait on the bottom. Top fit cling film and make a few holes with a thick needle. Put near the habitat of Drosophila. After a few hours, throw away the glass with the caught flies and make a new blank.

3. Packet trap. In a new bag with high walls, put the bait, leave for a while. When the insects fly in, quickly close the bag and take it out of the house.

4. Duct tape. Coat the tape for catching flies with wine or sour compote. Drosophila will fly to the smell and stick.

5. A bottle of formula. Pour juice or compote into a small glass bottle with a narrow neck. Add soap solution. Leave in a place of accumulation of flies. They will fly inside, but they will not be able to rise.

Here are some actionable tips to help stop fruit flies in your home:

• When a fly in pots of flowers is wound up, you need to stick a few matches into the substrate with their heads down. The mosquitoes will disappear.
• You can catch fruit flies with a vacuum cleaner if they interfere a lot and fly a lot.
• If there are plates from mosquitoes, then you can stick them on the window, from the sunny side. The smell will be deadly to the flies.
• To avoid the reappearance of these insects, you need to remove all the fruits in bags. Do not leave leftover food on the table. And spoiled products should be disposed of immediately.

Drosophila appears in the house very easily, but getting rid of it is not an easy task. If you apply the proposed methods correctly, you can get rid of these insects in a few days. But the best thing is not to give a reason for fruit flies to appear: do not leave food for a long time “unattended”.

To combat them, you can use various methods, including traps, which have the following advantages:

However, the use of traps also has some negative sides, the main ones are:

1. Low degree of effectiveness compared to the use of insecticides, which allow you to virtually instantly destroy entire populations.
2. No protective effect. Only those individuals that fall into the traps will be destroyed.
3. It is necessary to wait for the moment when the fly pays attention to the trap and falls into it., while some other methods allow you to immediately proceed to the destruction of pests.

Types of traps

The classification of such devices is carried out according to the principle of their action today, in accordance with this criterion, the following varieties can be distinguished:

1. Glue traps are one of the most well-known and common varieties, and their popularity is due to their simple design, which makes them easy to use and low cost. You can use houses or adhesive tapes that are attached to any surface. This type of device has a double effect, since it allows you to catch both flying and crawling insects. However, it is recommended to use hanging adhesive tapes directly for the extermination of flies. Despite the fact that crawling insects cannot fall into such traps, they will be one of the most effective means against flies.
2. Devices containing baits poisoned with various types of insecticides. They are considered traps only formally, since in fact they are not intended to catch flies, but to attract their attention with food bait in order to cause poisoning and subsequent death. They are usually used to kill cockroaches or ant, fly control devices are not so widespread, since other options have a much higher degree of effectiveness.
3. Mechanical traps with various baits designed to collect trapped insects. Devices of this type are used to catch virtually all types of insects and flies in this case are no exception. Exist various options, but they all work in the same way: flies get inside a special container, attracted by the bait, but can no longer get out on their own.
4. Electric traps are the most innovative way to fight, there are models designed to destroy various kinds insects. To attract mosquitoes and butterflies, special lamps are usually used, into the light of which they fly, while for flies, devices with fragrant bait are suitable, which will attract them with their smell. After entering the trap, the insect will receive an electrical discharge that is fatal to insects, while it is not capable of causing any harm to humans or pets. Electric models are the most expensive, but they are designed for long-term use, because the traps only need to be cleaned of dead insects from time to time, after which they will be ready for use again. To date, there are two types of electrical devices: functioning after being connected to the home electrical network or powered by replaceable batteries. The second option is usually used for catching flies outdoors.

Traps Overview

Given the wide range of modern fly catching devices, it can be quite difficult to choose the most suitable option.

To make this process as easy as possible, the following is an overview of the most effective tools:

Aeroxon sticky tape is made in Germany and is the simplest fly trap. Its use does not require any additional costs, it contains only cellulose and ordinary glue, the device is environmentally friendly. Sold in sets, which include four skeins of tape at once, the price is 100 rubles.

The HELP trap also has an adhesive element in its design, designed to be placed on windows, so flies are caught shortly after entering the room. The main advantage is the almost complete invisibility of this device, which can be purchased you can for 80-100 rubles.

The Raptor trap can is especially effective for catching flies and other flying insects outdoors. It is enough to place the bait that comes with the kit inside the tank, and then close the roof. The jar can be placed on any surface or hung on tree branches, and insects that have got inside will no longer be able to get out. The approximate cost is 300-350 rubles.

FC001 is a mechanical fly trap. It starts working after a special tablet is inserted into it, after which the device produces heat and smells that attract insects. It is enough to have no more than 2-3 tablets in stock, this amount will be enough for the entire warm season. The price is about 3500 rubles.

The Excalibur Aqua 80 IPX4 ZSP005 is a unique tool and trap designed specifically for flies, which has no analogues on the market today. The device is recommended for installation in places Catering, in large enterprises or logistics centers, although it can also be used in residential areas. The basic principle of operation is to defeat insects with deadly electrical discharges. The body is made of high-quality and high-strength polycarbonate, and the trap itself is provided with a moisture protection system, which makes it unpretentious to environmental conditions. The approximate cost is 50,000 rubles.

"SKAT 23" is a trap of domestic production, which, in addition to flies, allows you to destroy mosquitoes, which makes it a multifunctional device. The design includes lamps of a special type that do not emit heat, but attract flying insects. As soon as they touch the protective grid, they receive a deadly electric shock. The device is environmentally friendly, silent and does not emit any third-party odors, while its the price is only about 4000 rubles.

Flypod ZF050 is not only highly efficient in operation, but also attractive design, which allows the device to harmoniously fit into virtually any interior. The combination of this factor with small dimensions and features of functioning makes the trap look like a small decorative lamp. Best suited for placement in public areas, cafes or living rooms where you don't want to use duct tapes that don't look very attractive. Insects die when they get inside and come into contact with an adhesive liner, which can then be replaced with a new one. The approximate cost is 8500 rubles.

Fly Web Fly Trap is a trap that has not yet become widespread in the domestic market, but it can be ordered via the Internet. It has several effects, including light, which allows you to attract not only flies, but also a number of other flying insects. The device is a consumer of energy, so it can only function after being connected to the mains. The only drawback is the fact that it is extremely attractive to butterflies, moths and other harmless insects, which are also likely to fall into it. The cost of such a trap, excluding delivery, is about 2000 rubles.

The Sterling Rescue Outdoor Fly Catcher Trap is also currently an online-only model. Outwardly, it is a reservoir bag made of durable plastic. To start operation, you need to add a small amount of water inside, and then hang the device in the apartment or on the street. Inside it is a special attractant, which is quite attractive to flies and attracts them to itself. . The captives who got inside will no longer be able to get out, one trap is designed for 20,000 flies, after which it is disposed of. It must be used carefully so as not to damage the tank, and also place them in safe places, because over time, larvae may begin to breed inside. The approximate cost is 800 rubles, excluding delivery, two devices are supplied in the kit at once.

A plant called Venus flytrap is not a deterrent, but a real fly trap. In its natural environment, it grows mainly in swampy areas, where the soil is not fertile and actually does not contain nutrients. To compensate for them, this flycatcher eats insects, and flies form the basis of the diet. Such a plant can be planted in the territory garden plot or grow in a pot like indoor plant. It is recommended to keep it on the windows from the sunniest side and the Venus flytrap will not only decorate the apartment, but also a real thunderstorm of flies that have flown into it.

DIY fly traps

The purchase of store fixtures is not prerequisite, since there are a number of ways to make traps yourself.

To implement this idea, you must use the following algorithm of actions:

1. Prepare a small glass jar in which you need to pour the juice. It should fill no more than a third of the container.
2. Add a few drops of soap or dishwashing liquid to the liquid bait, which will eliminate the possibility of a possible escape of caught insects.
3. Fold a piece of paper like this so that it takes the form of a cone, the diameter of one of the holes of which should not be more than 5-8 mm.
4. Paper cone is inserted narrow side inside the jar.
5. Flies will get inside homemade device through a small hole, after which they will either sink into the liquid or remain sitting on the inner walls of the jar.

To do this, you will need to repeat the following sequence of actions:

1. Mix equal amounts of castor oil and rosin.
2. Melt the mixture and add a small amount of honey and jam to it, which will be the main bait.
3. Cut out paper strips, the recommended width should be 5-8 cm.
4. Process both sides of the cut strips prepared mixture.
5. hang up makeshift trap in places, where a large number of flies usually live, after which they will begin to stick to its surface.

How to make an insect trap? This question is asked by all summer residents and residents of private houses. Wasps, flies, mosquitoes begin to besiege a person on hot summer days, especially in July and August. At this time, young offspring appear, which needs a lot of food. Therefore, males and females scurry about in search of food. They fly for food, especially for sweets and meat. Mosquitoes annoy with painful bites.

Many people are allergic to wasp stings. Therefore, people have to apply many methods of insect control. The bites of these insects are very unpleasant, especially for children. Sometimes you have to call ambulance to avoid suffocation due to an allergic reaction. Getting rid of wasps is the easiest. You can try to find the nest and destroy it. But wasps fly around the site. Mosquitoes can crawl into every crack in the house, as can flies. Therefore, you need to know how to make a trap at home.

Effective trap for wasps and flies

There is a very effective device that has been tested by many site owners. To make it, you need a 1.5 or 2 liter plastic bottle. The cover should be removed from it. The bottle must be cut into two components. The top part should be half the size of the bottom. Inside you will need to place a liquid bait. So that it does not spill, you need to place the upper part in the lower neck inside. On this trap can be considered ready.

Any sweet liquid can be used as bait. But it is best to take fermented compote, as it has a sharper smell. This completes the instruction on how to make a trap. Insects will fly to the smell and get inside, but they won’t be able to get out. Trying to crawl out along the walls of the bottle, a wasp or a fly gets into a dead end, which is formed due to the upper neck. It is better to make several such baits. They should also be reinforced in case of strong winds.

What bait is better to take

Flies are different, so certain baits should be used for them. Houseflies and similar species are most fond of sweets. Large species are practically not interested in sugar, so it is better for them to put fresh meat or fish in the bait. fruit flies may be interested only in fruit, juice or compote. Wasps are most fond of sugary sweets, such as honey. From mosquitoes, unfortunately, such traps will not help.

Such devices are very effective. But there is a certain type - fruit flies, which rarely fly inside the jar. The way to make a trap for them will be discussed a little lower. The funnel trap is not suitable for home use. It's all about bad smell, which begins to come from the bait after a few days. But if you change it more often, then the trap is quite suitable for the premises.

Do-it-yourself sticky fly tape

The most common way to get rid of flies is with Velcro tape. These are sold in every hardware store. Flies willingly sit on the tape, as glue is applied to it, which contains bait. An insect cannot fly away from such a device. The tape works for a while, but then the glue dries up. The advantages of such a device are many. It is affordable, harmless to humans. The tape does not smell, does not emit toxic substances.

How to make this type of fly trap? Many people think that this is impossible. But in fact, you can make a tape quickly. To do this, you need to take linen or Castor oil, resin or rosin. As a bait, you need to take glycerin, honey or sugar. Melt all the ingredients in a water bath and apply them on a paper tape. It will turn out an excellent analogue of a store device. Just such a tape is suitable for catching fruit flies, as they like to sit on the surface.

Now readers know how to make a trap for wasps and flies. Surely many are also interested in what goals the insect pursues. If bees live to make honey, then flies and wasps pursue completely different goals. They try to lay as many eggs as possible. One fly manages to reproduce up to 2000 larvae. And they live only a couple of months, and sometimes up to two weeks. For one laying, the fly lays about 120 eggs.

A cesspool, a compost heap, and even soil in a flower pot are most suitable for this. The fly will appear in a couple of weeks. Moreover, the warmer the ambient temperature, the faster the larva matures. Flies hibernate in winter. Active life begins only when the daily temperature in total is +20 degrees. There is one more interesting fact. Surely many are interested not only in how to make a trap at home, but also in why flies always sit on the windows. They just have compound eyes, because they simply do not notice transparent objects.

Why are flies dangerous?

Insects, in particular flies, are carriers of many diseases. Therefore, it is important to get rid of them in time. If wasps are dangerous due to bites, then flies can cause not only food poisoning, but also the most dangerous diseases. Here are some of them: typhus, fever, cholera, dysentery, brucellosis, etc.

An unusual but easy way to get rid of flies and wasps

Not everyone knows how to make a trap with their own hands using a fly agaric. Surely no one thought about the origin of the name of this fungus. It is necessary to collect fly agarics in August. A few hats will suffice. They should be crushed into disposable tableware and pour sweet water. A plate with mushrooms should be placed in the garden or in another place of mass accumulation of insects. Wasps and flies will immediately respond to the bait. You can not even crumble fly agarics, but simply sprinkle the hats with sugar. A syrup forms on the surface, to which insects will stick.

How to get rid of mosquitoes

To fight mosquitoes, you can make an ordinary trap-non-spill, but there is a more advanced tool. It is worth trying to make an electromechanical device. To create it, you will need a few improvised materials. The main component of the trap is a motor powered by electricity. Thanks to him, the trap has a suction effect. It draws mosquitoes inside a special container from which they cannot get out.

How to make a mosquito trap of this type? Everything is very simple. The power supply is based on direct current. A regular cooler can become a fan for the device, only, preferably, large sizes. For the basis of the case, you can take a plastic bucket from under the mayonnaise. In the bottom of the jar, you need to make a hole equal in diameter to the size of the cooler. Typically, the fan is sold complete with screws. They can screw the device to the bottom of the bucket. The cooler is attached outside, not inside.

bait for the trap

A suitable bait will be a light bulb with a bayonet base, as well as a cartridge for it. The surrounding air will heat up and at the same time illuminate the space. Everyone knows that light is the main bait for insects. LEDs can be used instead of light bulbs. Moreover, it is more economical to buy them in a tape, and not separately. In addition to light, you will need another bait. Mosquitoes will be interested in carbon dioxide, to obtain which you will need to dilute the same amount of sugar and 5 g of yeast in 0.5 cups of water. The bait should be added to the container, which must be attached to the body of the trap.

These are the lungs, but effective methods to control flying insects. They are much safer than aerosols and other chemical substances. Therefore, it is better to spend some time on independent production traps than to waste cash to other pest control methods.

Everyone loves summer, but we're sure no one likes the sudden increase in creepy insects that breed at an alarming rate during the warmer months.

At the same time, no matter how clean you keep your house, there are flying aliens who stubbornly try to get into it and with varying degrees of difficulty they sometimes succeed.

And after that, the insects simply do not want to leave the comfortable dwelling of a person. Therefore, people have to invent the most different ways to get rid of uninvited guests. And here the ability to think creatively often comes to the rescue.

For example, Imgur user Donkey1521 came up with a simple fly trap made from a regular plastic bottle. It is easy to make and non-toxic, while fighting the most different types flies - from large dung to small fruit flies.

In order to get started, you only need a few things: for the trap itself, you need a plastic water bottle, and for the bait, a banana and granulated sugar.

Imgur/Donkey1521

First, you need to cut the bottle in two using scissors or a sharp knife. To do this, mark the cut at a distance of about two-thirds of the height of the bottle from the bottom, and then go around the circumference with a cutting tool. When you're done, you should have two pieces: a smaller one with a lid and a larger one that can sit on a table.

Imgur/Donkey1521

Pour about one tablespoon of granulated sugar into the larger part of the bottle until the bottom is coated. Then cut ripe or slightly overripe bananas into small pieces.

Imgur/Donkey1521

Place the sliced ​​banana on the sugar in the bottle; this sweet mix will help lure flies that feed on decay products and decaying organic matter.

Imgur/Donkey1521

Once you have the banana and sugar in the bottle, lightly mash them together to form a sort of puree. Add about 4 centimeters of warm water to the puree and lightly stir the mixture. warm water and sugar will cause the banana to rot faster, making it a more powerful fly bait.

Imgur/Donkey1521

Now that most of the bottle is done, it's time to move on to the smaller part. unscrew plastic cover and turn the smaller part upside down. Then place the smaller portion inside the larger one so that the hole is in or directly above the banana mixture. Your trap is now ready for use.

Imgur/Donkey1521

This trap can be used for about a week. During this time, its lower part should be filled with flies. After a few days, it may start to look a little nasty, but it's worth it to get rid of any flies in your home.

Imgur/Donkey1521

Here's a close-up of how a fly trap works. The flies move down through the neck of the bottle at the bottom towards the banana bait. After that, they struggle to get out through the hole and drown inside the bottle. Cruel, but it does its job!

Imgur/Donkey1521