Onion Fly at Home

The onion fly, also known as the leek fly, is a parasitic insect commonly found on onion plants. Although this pest can also attack other plants, such as garlic or flowers from the lily family. Usually the presence of onion fly is easily noticeable: the growth of onion plants slows down, they begin to dry out, wither and turn yellow, and their smell also changes. The bulbs of infected plants become covered with a putrefactive coating, become soft and are no longer suitable for consumption. Therefore, onion fly is a serious problem for gardeners.

In this article we will tell you what the onion fly is, why this harmful insect occurs, what are the main signs of its presence and what means will help you save your crop from this pest.

Onion fly. general characteristics

The onion fly looks like a small light gray midge and reaches about one centimeter in length. Males have a dark stripe on their abdomen.

These pests actively reproduce, laying up to 60 eggs during their lifetime. The eggs of the onion fly are white, about 1 mm long, with a longitudinal stripe. She lays eggs both on the leaves of the onion and on the part of the bulb protruding from the ground.

The larva hatches after about a week and begins to feed, accumulating nutrients, and then enters the pupal stage. The adult onion fly emerges from the pupa after some time, ready to begin a new breeding cycle. This occurs early, in mid-spring, making this fly especially dangerous to plants.

What harm does the onion fly cause?

The greatest threat to the crop is not adult onion flies, but their larvae. Adult insects feed on the nectar of flowers and do not directly harm the plants, except by laying eggs on onion plants. These eggs hatch into larvae that begin to actively eat away at the onion, gnawing passages inside the bulb and consuming its inner part. With a significant number of larvae, large cavities can form in the bulb.

This leads to rotting processes inside the bulb, from which a characteristic odor begins to emanate. Naturally, such a bulb cannot be used either for planting or for eating. The larvae can completely destroy the bulb within two weeks.

The first generation of larvae poses a particular danger to the crop, since they hatch during the period of rapid growth of onions. Simply pulling infected plants out of the ground is not enough, because the larvae remain in the soil and wait until winter to become active again next year.

How to recognize an onion fly infestation?

If your bulbous plants begin to turn white or yellow, dry out, and smell rotten, these are clear signs of onion fly infestation. To make sure there is an infection, you can dig up one or two bulbs and carefully examine them by breaking them into pieces. Infected bulbs lose their firmness and become loose and soft. Inside the bulbs, the larvae are clearly visible - small whitish worms.

Let's look at the main signs indicating the presence of an onion fly:

1. The leafy part of the plants dries;
2. The bulbs turn yellow and become soft. Some of them have cavities and passages dug by larvae;
3. There is a putrid smell coming from the onions;
4. Adult onion flies circle around the onion.

Why does the onion fly appear?

There are several reasons for the appearance of onion flies on the site. Here are the main ones:

1. Using material for planting onions infected with these parasites;
2. Lack of crop rotation or its incorrect implementation;
3. Neglect of autumn digging of the earth;
4. Failure to comply with onion planting deadlines;
5. Incorrect location of crops on the site relative to each other.

Interesting facts about the onion fly:

• Spread: The onion fly lives everywhere where onion crops grow, including Europe, North America and Asia. It can be found at an altitude of more than 3000 meters above sea level.
• Affected plants: Pests for bulbous plants of the Liliaceae and Kasatikov families are all types of onions, garlic, lilies, tulips, irises, and lettuce.
• Catering: Adult onion flies feed on the nectar of flowers, while the larvae feed on the pulp of the bulbs and green parts of the plants.
• Laying eggs: Typically, the female lays from 30 to 60 eggs per clutch.
• Number of generations per season: In temperate latitudes, the onion fly produces 1-2 generations per season, but in the south this number can reach 3 generations.
• Wintering: The onion fly overwinters in the soil at a depth of up to 20 centimeters.
• Activity period: This pest begins to damage plants in June, although in the southern regions this period may begin earlier (second generation).

How to deal with onion fly?

In large onion plantations, insecticidal agents such as pyrethroids, organophosphates and neonicotinoids are often used to control onion flies. Among the common drugs are Diazinon, Imidacloprid, Thiamethoxam, Dimethoate and others. These liquids are sprayed directly onto the plantings. There are also preparations for home use, such as “Mukhoed”, “Sochva”, “Alatar” and others. It is important to follow instructions and practice safety precautions when using these chemicals.

For those who prefer to avoid chemicals in their area, there are many folk remedies against onion flies. Below we will look at the main ones.

Tobacco dust

This product is very popular among summer residents and gardeners. It can be purchased ready-made; there is no need to go through the hassle of grinding the tobacco - the dust is sold in a convenient form. To combat onion flies, simply sprinkle the onion beds with this dust, using one level tablespoon per 1 square meter. If insects have already begun to fly actively, you can mix dust in equal proportions with mothballs or regular sand from the river. It is preferable to use mothballs, as its smell repels parasites. Another way is to mix ground hot pepper with wood ash and sprinkle the mixture on the soil. Instead of ash, you can take the same tobacco dust.

If flying adult onion flies have already been noticed on the site, you can use tobacco infusion. Dissolve 250 grams of tobacco in 10 liters of water, let it brew for two days, strain, pour into a spray bottle and treat the onions using 1 liter per square meter.

Ammonia

If you find frequent flights of flies over your onion planting and you are afraid that they will soon begin to lay eggs, ammonia is an effective way to combat them. It is advisable to start treatment as early as possible, since later the pests become more resistant. Dissolve 3 tablespoons of ammonia in 10 liters of water and spray the bulbous plants with this mixture. It is best to carry out treatment in the evening. It is recommended to repeat this procedure approximately once a month, 2-3 times throughout the season.

Wood Ash

Wood ash is a very effective remedy in the fight against onion fly, which is popular among many gardeners. It can be purchased at garden supply stores, but you can also easily make it yourself. To do this, simply burn dried branches, bark and pieces of wood.

There are two main ways to use wood ash to protect plantings from onion flies. The first method is to cover the onion beds with an even layer of ash about 2 mm thick. Alternatively, you can treat the onions with an aqueous solution of ash. To prepare the solution, dissolve approximately 500 grams of ash in 10 liters of water, then leave to infuse in a dark place for 1 hours, strain, pour into a spray bottle and spray the growing onions in the garden. Try to ensure that the solution gets onto both the plant and the soil around the plantings. Typically, approximately 1,5 liters of solution are required per XNUMX square meter.

salt brine

Treating onion beds using a saline solution is an effective method of killing the pest. However, it is recommended to use it carefully to avoid soil salinization. This procedure is recommended to be carried out no more than once a season and only taking into account crop rotation.

Typically, treatment is carried out 14 days after the emergence of onion shoots. To do this, dissolve 200 grams of salt in 10 liters of water (but no more!) and treat the soil with this liquid, avoiding contact with plant leaves. It is recommended to carry out the procedure in the evening, and the next morning to water the bed generously with soft water.

Onion fly larvae. How to deal with them?

We have already discussed methods of combating adult onion flies, let’s now move on to destroying its larvae. If you find both the insects themselves and signs of yellowing and wilting of the plants, you should immediately treat the onion beds with a mixture of naphthalene and river sand (in a ratio of 10:1). Try not to form a continuous layer, but simply sprinkle the soil evenly with this mixture.

Other effective remedies against the larvae of this pest are decoctions of valerian, pine needles, wormwood and mint. For valerian, you need to use half a kilogram per bucket of water, enough to treat 3-4 square meters. Needles are used in a dosage of 50 to 100 grams per 1 liter of water, which allows you to treat 1 square meter. For wormwood, fill 1/4 of a bucket with water and leave to steep for 2 hours (one bucket per 3-1 square meters), and use mint in the amount of 3/3 of a bucket per 4-XNUMX square meters.

A popular method of combating onion fly and its larvae is to treat plants with liquid antibacterial or regular laundry soap. To do this, take 50 grams of liquid soap or half a piece of laundry soap per bucket of water. The water should preferably be soft, preferably rain. The solution can be sprayed both on the soil and on the plants themselves. It is most effective to wet the plants, especially if they have already begun to dry out. This treatment can be carried out up to three times with an interval of 7 days.

Some gardeners prefer to use kerosene as a proven insect repellent. Its main advantage is that it is almost completely safe for the soil, people and animals, while it is fatal to pest larvae. Kerosene should be thoroughly diluted before use. One bucket of water requires only 50 grams of kerosene. With this solution it is necessary to spray the soil around all the bulbs.

To prevent the return of the onion fly after harvesting, it is recommended to carefully and deeply dig the beds. In this case, it is better not to loosen the soil too much, so that the maximum number of larvae die from the cold.

How to prevent onion flies?

Taking the necessary preventive measures is much easier than dealing with onion fly later. Therefore, discussion of this aspect is as important as methods of controlling flies and their larvae.

To avoid the appearance of onion flies in your garden, it is important to adhere to the rules of crop rotation. Onions should be planted in the same soil no earlier than every four years. During this time, the parasites will simply disappear, having lost their food source.

Every autumn, after harvesting, it is recommended to dig up the beds. This should be done to the full depth of the shovel, while avoiding crushing lumps of earth. Onion fly larvae are able to burrow into the soil to a depth of 20 cm and spend the entire winter there. Digging up the area helps reduce their number.

Another important tip is the proximity of onions to carrots. The smell of carrots repels onion flies. It should be noted that there is a carrot fly that cannot tolerate the smell of onions. In addition, carrots and onions go well together.

Before planting the bulbs in the soil, carefully inspect them for larvae. To destroy them, soak the bulbs in a saline solution (1 tablespoon of salt per 5 liters of water) at 45°C for 10 minutes. You can also slightly immerse the bulbs in water with the addition of 1% potassium permanganate for a few minutes.

If the degree of damage by the larvae is too high and they have already penetrated inside the bulb, the plant cannot be saved - it should be dug up and destroyed.

When planting onions in your area, try to adhere to the planting dates. This will allow the bulbs to grow sufficiently before the larvae hatch, while reducing damage from pests. During the season, regularly cultivate the area - loosen the soil, avoid crust formation and remove weeds.

If onion flies frequently appear in your area and you do not want to use chemicals, reduce the amount of watering of the bed - this will help dry out the soil surface and may prevent the larvae from hatching. Wait a week, then resume watering your plants as normal.

Perhaps you have a question: “Why loosen the soil in the beds?” The fact is that loose soil is not particularly attractive to onion flies, so they rarely lay eggs in it. If it is difficult for you to regularly loosen the surface of the beds, you can mulch it with wood ash or humus. The layer thickness should be about 1 cm. At the end of the summer season, remove this layer and remove it - there may be onion fly larvae or eggs there.

If the risk of onion fly infection is high or has already reached serious proportions, it is recommended to remove snow from the onion bed in winter. This way the soil will freeze to a great depth, and the larvae will not be able to survive in such conditions. For maximum efficiency, combine snow removal with deep digging of the soil without breaking up lumps.

F.A.Q.

How to quickly get rid of onion flies?

There are many ways to kill onion flies. One option is chemical preparations such as Sochva, Alatar and Muhoed. In addition, there are folk remedies, for example, treating the beds with tobacco dust, wood ash, ammonia or salt solution. It is worth noting that the saline solution should be used no more than once per season.

How to destroy the onion fly larva?

Methods for destroying onion fly larvae are as varied as methods for controlling adult insects. This may include sprinkling the beds with a mixture of naphthalene and river sand in a ratio of 10:1, spraying with herbal infusions (wormwood, mint, pine needles and valerian are suitable), using a solution of soap or kerosene. Digging the beds is also an effective remedy.

Why does the onion fly appear?

Onion fly can appear for several reasons. One of them is the use of initially infected bulbs. Also, neglect of crop rotation, incorrect timing of planting onions, or failure to dig up the soil after harvesting can contribute to the appearance of this pest.