Meadow gnats: recognize damage and fight larvae biologically

Meadow gnats don't sting, but they can still cause a lot of damage. To be more precise, it is their larvae that can cause entire lawns to die off in an emergency.

Even if it is in the case of meadow gnats (Tipula paludosa) are basically useful insects, mass occurrence in the lawn can quickly become a problem. In this article you will find out how to recognize the damage, the adult animals and the larvae of crane flies and various ways of combating them in an environmentally friendly manner.

Recognize the meadow gnat: way of life and damage

Despite their middle name - Sumpfschnake - one finds meadow gnats mainly on fresh, medium-heavy, loamy soils with closed turf. Crane flies are fairly easy to spot and distinguish from other insects and their larvae.

Adult crane cranes are relatively large with a body length of up to 2.5 cm and a wingspan of 3 to 4 cm. The body of Tipula paludosa is uniform grey-brown and elongated. Their legs are noticeably long and thin, and their wings are clear and not spotted. If one observes a specimen more closely, one notices a V-shaped seam on the back and the lack of pinpoint eyes between the compound eyes. As with all types of gnats, the mouthparts of meadow gnats are not suitable for stinging. Instead, the adult animals feed on water and nectar. So they are neither dangerous to us humans, nor do adult meadow gnats damage the lawn.

Tip: At first glance, adult meadow gnats can be compared to the so-called cabbage gnats (Tipula oleracea) to be confused. For a definitive identification, you have to catch a mosquito and look at its eyes. If they are close together and almost touching, it is a cabbage fly. In the case of meadow gnats, the distance is much larger.

Immediately after hatching in autumn, the larvae of the meadow gnat are still very small. However, they grow to a size of up to 4 cm by next spring. The so-called "devil's face" is typical of tipula larvae. Looking at the brownish-grey larva from behind reveals a dark, hard plate surrounded by six white lobe-like appendages. It is a tool used for locomotion. But it was interpreted by creative viewers as a face with two dark eyes and white horns. The actual head capsule is of solid structure and very small. Furthermore, the larvae have neither legs nor any other appendages.

Tip: Despite everything, it is very difficult to distinguish the larvae from other species of gnats. However, the distinction between Engerlingen, which can also cause great damage to the lawn. The larvae of meadow gnats are significantly slimmer than grubs and do not show any noticeable thickening or curvature of the body.

The pupae of the larvae during the resting stages are reddish-brown and divided into several segments, the posterior ones of which bear ring-shaped small spines.

way of life

The adult animals hatch from the pupae around mid-August. Because of their short lifespan, the crane flies start mating and laying their eggs right away. Since the females are only able to fly to a limited extent and can only manage a maximum of five meters at a time, they are only found near the habitats of larvae. A female lays 300 to 500 eggs and then dies relatively quickly. The first larvae hatch after 11 to 15 days. A total of four stages are passed through before pupation, two of them in autumn. The third instar larvae occur deeper in the soil and allow hibernation below the frost line. In cold winters, up to 50 percent of the larvae of Tipula paludosa enter. However, if the winter was mild, the majority survived. In the spring, development continues with the last two larval stages. This is where the greatest damage is done, because in the final stage the larvae can grow up to 4 cm long and are therefore real wolverines.

Around the middle of May, the meadow crane fly larvae have reached their maximum size. Then they migrate deeper into the soil and lay a nest about 3 to 5 cm below the soil surface about six weeks of dormancy before pupating and as adults from mid-August Hatch. In this way, the meadow cranefly creates one generation per year.

damage picture

As early as autumn, the still young, small meadow gnat larvae feed on grass roots and at night or on rainy days also on superficial parts of plants. However, the main damage occurs in spring, especially after mild winters. Then the masses of large meadow crane fly larvae can uproot entire lawns.

Typical signs of an infestation with larvae of crane flies are:

• Decreased growth
• Yellow-brown discoloration of leaves
• signs of wilting
• Clusters of bald spots
• More birds on the lawn. They eat the larvae that live near the surface of the soil and can further damage the grass by scratching.

Difference to fungal diseases: In the case of a meadow gnat infestation, leaves turn uniformly brown and not blotchy. It looks as if the lawn is drying up in places.

If you are unsure, a simple groundbreaking in an affected area will help. In the event of an infestation, you should be able to see the larvae directly, of which up to 600 per square meter can occur in severe cases.

At a glance: What do the meadow gnats look like in the lawn?

• Adult crane flies: Length: up to 1.8 cm (males), 2.5 cm (females); wingspan: up to 3 cm; long, thin legs; solid, brownish gray with clear, immaculate wings.
• larvae: brownish gray; up to 4 cm (in spring); sclerotized, small head capsule; "Devil's face" on the abdomen for locomotion.
• dolls: reddish brown; different segments, the posterior ones with small spines.
• damage picture: Withering and brown discoloration of grasses up to clusters of bare spots in the lawn.

Combat grasshoppers

Once you have discovered the first flies in your garden, the question quickly arises: "How do I fight Tipula larvae in lawns?” The synthetic-chemical control of meadow crane fly larvae in lawns has been around for some time forbidden. However, there are still a variety of control options, some of which are very compatible with the environment and leave other useful insects in the soil unharmed.

Nematodes against meadow crane fly larvae

nematodes of the species Steinernema carpocapsae parasitize the larvae of crane cranes and some other pests. The tiny roundworms, which cannot be seen with the naked eye, look for the larvae in the soil and penetrate them. There they continue to multiply and thereby kill the meadow crane fly larvae. It does this by releasing a bacterium, which in turn releases a toxin. The first treatment successes are already visible after seven days. When the old larva runs out of food, the nematodes abandon it and go in search of new hosts. This goes on until they run out of larvae and eventually die off themselves. Combating crane runners in the lawn with nematodes is a sustainable, chemical-free method that is harmless to humans and the environment. An efficiency of 80 to 90 percent can be achieved.

Combating crane flies with nematodes only makes sense between mid-September and mid-October, So two to three weeks after the flight of the imagines, the fully formed and sexually mature Insects. With increasing age, the larvae develop better defense mechanisms and become more and more resistant. During this period, our Plantura SC nematodes Used against mole crickets, crane flies and cutworms. A packet with ten million nematodes is enough for about 20 square meters. The nematodes can be conveniently ordered and delivered to your home. They can be stored in the refrigerator for up to six weeks before use.

Tip: Choose a cloudy, rather rainy day for the application, because the nematodes are sensitive to UV radiation. Even after that, the soil should always be kept moist, otherwise there is a risk that the nematodes will dry out.

Insecticides against meadow gnats

In grassland and on lawns, no insecticides are generally permitted to control the crane fly. Apart from that, these synthetic substances often affect other beneficial insects in addition to their intended effect. They can also have negative effects on us humans or pets. Luckily there is no need for insecticides against crane flies, because there are plenty of other ways to combat them.

Fight meadow gnats with calcium cyanamide

The best effect with calcium cyanamide against Tipula is achieved when the fertilizer is applied in early spring, i.e. from around March. The younger the larvae are, the more sensitive they are. The soil temperature should already have reached 3 – 8 °C. If 30 to 40 g of fertilizer per square meter are then applied on rainy days, efficiencies of 40 to 60 percent can be achieved. But beware, in the long run, fertilizing with calcium cyanamide also has many disadvantages, as you can see in our special article Calcium cyanamide fertilizer can read.

Home remedies for meadow gnats

The larvae can also be controlled mechanically, for example by rolling the lawn while the larvae are still in an early stage of development. Aerating rollers with spikes are particularly suitable here.
scarify also causes lasting damage to the larvae, but also to the lawn. Therefore, one should avoid verticulating with a overseeding combine.
On small areas you can also distribute coasters with a bait mixture of ten parts moist wheat bran and one part sugar. The tipula larvae in the lawn are strongly attracted to this, leave the ground and go into the saucers. There they can then be collected in the early morning hours. Pieces of black foil or plastic have a similar effect.
Finally, you can also cover small lawns with fleece as soon as you spot the first flying gnats in August. This prevents the gnats from laying their eggs in this patch of grass. It is important that the fleece is as light as possible and permeable to air and water so that the lawn is damaged as little as possible. Only remove the fleece for lawn mowing. The last adult animals die around mid-September, so that the fleece can then be completely removed from the lawn.

At a glance: How can you fight the meadow crane fly?

• Responding with synthetic insecticides is not allowed.
• Nematodes represent a sustainable, safe control option. The tiny roundworms kill the meadow crane fly larvae in the lawn by parasitizing them.
• Fertilizing with calcium cyanamide can affect the meadow crane fly larvae, with calcium cyanamide being detrimental to the lawn in the long term.
• Rolling and scarifying can also kill crane fly larvae.
• Bait traps lure larvae out of the ground, which can be collected.
• Small lawn areas can be covered with fleece.

Prevent an infestation

Some of the measures mentioned above also serve to prevent a meadow gnat infestation. For example, you can prevent egg laying by covering the lawn with fleece, foil or cardboard. Occasional rolling or scarifying also keeps them in check. In addition, the promotion of predators of meadow gnats counteracts an infestation of your lawn. This includes many birds such as blackbirds and starlings. As your Make garden more bird friendly can, we have summarized in an extra article.

A healthy, lush green lawn requires a lot of care. Because not only pests, but also fertilization at the wrong time or incorrect mowing can affect the lawn. So it's important to know which ones Maintenance work for the lawn is pending all year round and what to watch out for.