Mole cricket - benefits, harm and control measures

Get to know and drive away mole crickets

the essentials in brief

The mole cricket belongs to the grasshoppers, but lives mostly underground and creates there meter-long and up to four meters deep tunnel systems.
The insect feeds almost exclusively on maggots, worms, eggs and other animal food, which is why it is actually classified as a beneficial organism. The claim that mole crickets also eat roots and tubers is simply wrong.
However, if the population in the garden is too large, the animals can still cause considerable damage due to their heavy burial activity.
They can be best combated with nematodes, especially since the classic home remedies are not very suitable and there are no effective chemical control agents for the home garden.

Appearance and way of life of the mole cricket

The mole cricket bears its name for a reason: its large grave shovels and their underground way of life are strongly reminiscent of the mole, and the insect belongs to the grasshopper family (lat. Orthoptera), resembles a large cricket and also makes very similar sounds. There are different types of mole crickets, but only the European mole cricket (lat. Gryllotalpa gryllotalpa) is at home in this country.

Profile: The mole cricket at a glance

Type: European or Common Mole Cricket
Latin name: Gryllotalpa gryllotalpa
Popular names: Werre, G'schwer (Austria), Zwergel, Halbteufel (Switzerland)
Class: Insects (Latin Insecta)
Subclass: flying insects
Order: grasshoppers (lat.orthoptera)
Subordination: long-feeler horror (lat.
Habitat: in loose, preferably sandy to loamy soil, often near water and on meadows, lawns or in gardens
Occurrence: Europe, North Africa, West Asia
Special features: digs tunnels several meters long and up to four meters deep

This is what the mole cricket looks like

Anyone who sees a mole cricket for the first time is sometimes frightened: The up to ten centimeters long, primeval cancerous-looking animals look clumsy and bulky. Especially when such an insect buzzes flying through the garden during the mating season, many a garden owner becomes drowsy.

But mole crickets are completely harmless. In addition, they spend most of their lives underground in the ground, which is why they are perfectly physically adapted to this life. Its body is protected by a thick chitin cover, and the insect digs its many meter long tunnels with its characteristic large grave shovels.

Size : usually between four and six centimeters, in exceptional cases larger
Color : light to dark brown, matt-glossy, the underside often lighter than the upper side
Physique : strong, primeval, body is covered with fine hair
Head : large, well protected with chitin armor
Legs : four-limbed front legs, which are shaped into digging shovels, inconspicuous - - - - - hind legs : (no jump legs as with other grasshoppers)
Wings : short fore wings, longer hind wings protruding beyond the abdomen
Special features : generates a loud, humming noise with the wings during the summer months

You can hear what the chirping of the mole crickets sounds like in this post:

Youtube

Mole crickets are grasshoppers, but unlike their relatives, they cannot jump. Although the animals are very loud and can hear themselves very well, they mainly perceive the sounds of their own species. The complex eyes that are otherwise typical of the species are also missing.

Occurrence and Distribution

The European variant of the mole cricket has become rare, even if some troubled gardeners can hardly believe it. The main reason for this, by the way, is the strict control of animals in the garden and in agriculture, as the insects often settle in compost and dung heaps as well as in vegetable gardens and find ideal living conditions there. Mole crickets prefer loose, cultivated sand and clay soils, which should also be moist. For this reason, the animals are more likely to be found near bodies of water.

The various species of the genus are found almost everywhere on earth, with most of the populations found in the Mediterranean region. In Germany, mole crickets are mainly found in southwest Germany, but are almost unknown in the north.

Way of life and reproduction

Mole crickets create meter-long tunnel systems in the garden, which mainly consist of channels running close to the surface of the earth. From these horizontally running tunnels, further tunnels extend up to four meters deep. These serve as access to the lower lying storage and feed chambers as well as to the incubation chambers. While the individual corridors are often no wider than about six centimeters, the chambers can reach the size of tennis balls or even football. They are reinforced and secured with parts of plants, which the animals press with their solid armor into the earth walls. Mole crickets are very busy and dig up to 40 meters per day.

The mole cricket spends almost its entire life underground, only during the mating season between early May and mid-June does it leave its original habitat. The nocturnal animals can only be seen in the evening and night hours. Only the females can fly and in this way follow the mating calls of the male mole crickets. After mating, the female lays up to 1000 eggs (but mostly only between 100 and 300) in an underground brood chamber, which it sticks to the cave walls. The eggs are guarded and cared for by the female, the larvae hatch after about seven to twelve days.

The development of the mole cricket at a glance:

Larvae go through a total of six to ten different stages.
This development takes place over a period of around two years.
The larvae spend the first four to six weeks in the burrow.
They are cared for by the female and feed on dead plant parts.
They only leave the nest after the first molt.
They molt a total of three times by autumn.
The larvae overwinter in the ground and molt a fourth time in spring.
At this point, they can move very quickly.
These larvae - in contrast to the adult animals - can still jump.
At the end of July of the second year, the animals are already fully developed.
However, sexual maturity does not take place until the following year.

Due to the long development time, larvae and adults of all stages of development and age are typically found in a garden infested with mole crickets.

What does the mole cricket eat?

"Mole crickets don't eat vegetables!"

It used to be assumed that mole crickets prefer to eat roots. Therefore, the animals were massively persecuted. It is now known, however, that the animals eat almost exclusively carnivorous: worms, maggots, larvae as well as insect and snail eggs are on their menu. Only very rarely, and when there is a pronounced food shortage, do mole crickets attack plant-based foods in the form of roots and tubers. The undoubtedly occurring damage in the garden is therefore less due to the feeding than to the large-scale burial activity of the animals.

Digression

Pest or beneficial insect?

Due to their pronounced predilection for animal food, mole crickets are not clearly classified as garden pests. After all, the eager companions devour numerous pests such as grubs, snail eggs (which results in less hungry nudibranchs), vine weevils, etc. This means that the animals - provided they do not appear en masse in one place - are even valued as beneficial insects.

This is how you can recognize a mole cricket infestation

As a rule, you do not even notice whether the mole cricket is also comfortable in your garden. Usually there are only a few animals whose population is also kept low by their natural enemies - above all the mole. If the food supply is also abundant - in other words, the table is plentifully covered with maggots, larvae and eggs - mole crickets do not eat plants. The typical damage pattern can only be seen in the case of severe infestation and too few feed animals:

Feeding holes in radishes, potatoes and other tubers
Vegetables and ornamental plants that wilt mainly in spring
churned vegetable and ornamental beds
Seedlings and young plants pushed out of the ground
Seeds suddenly appear in inexplicable places
Lawns have brownish spots

Some of these symptoms can also be caused by other garden pests, such as voles. Older plants are typically quite well protected from the mole cricket, which is why, for example, in endangered regions you should only place strong and early vegetable plants in the bed. Voles, on the other hand, also nibble on the roots of older and larger plants. Also, mole crickets do not throw up piles of earth, which in turn are typical of moles and voles.

Fighting mole crickets successfully

As long as the mole cricket population does not get out of hand in the garden, the animals are even to be welcomed as pest eaters. In this case, however, make sure to keep the number of worms as low as possible with the help of their predators. Trapping and releasing living specimens is also a suitable way of limiting. However, if the infestation becomes too strong (e.g. due to a lack of predators) and the damage increases significantly, you will have to use heavier artillery. Certain nematodes, for example, are very suitable for this.

Lure predators into the garden

Basically, the mole cricket has only one enemy underground: the mole. The furry loner not only competes with the insect in its habitat, but also ensures that there is less food available - after all, the mole also lives on animal food and thus has the same menu as the Werre. On top of that, this is a real delicacy for moles and is therefore eaten with preference. It is not only for this reason that you should not rush to drive moles out of the garden, even if the piles of earth occasionally disturb. The little graves keep garden pests at bay.

If the mole cricket comes to the surface, other garden dwellers also hunt the insect. Especially for

Hedgehog
Shrews
Birds
Ants

As well as chickens and cats, the insects are a treat. It is not without reason that chicken keepers are advised to let the poultry run free - they scratch and peck beetles, maggots, larvae and other insects from the loose soil and thus ensure that the garden remains as pest-free as possible. The disadvantage, however, is that chickens in the vegetable garden are actually not a good idea - they also like to pluck seeds, sprouts and young plants or eat their fill of lettuce instead of mole crickets. But chickens are very good at keeping a lawn free from the pests.

Otherwise - not only to keep the garden free from mole crickets, but also free from other pests - it is important to ensure that management is as natural as possible. This includes measures like these:

no toxins in the garden
i.e. no pesticides, herbicides, insecticides, fungicides etc.
These also poison useful garden dwellers.
Set up or hang up feeding places and incubators for birds
Build insect hotels in strategically and climatically good locations
Create hiding places for larger animals: piles of stones and wood in a garden corner, e.g. B.
Prefer native plants in the garden
especially many umbellifers, these attract useful insects

In such a garden, plant protection measures are less necessary because the biological balance is created and maintained in a completely natural way. Mole crickets have no chance of reproducing too much.

Tips

Digger wasps of the species Larra anathema also hunt mole crickets and were therefore brought in from their actual home, the Mediterranean region, specifically for pest control. Unfortunately, this digger wasp prefers dry, warm settlement areas and therefore does not feel particularly comfortable in Germany.

Set up traps

Quite effective and animal-friendly, but it is also quite laborious to catch mole crickets. The best way to do this is as follows:

Take several smooth-walled mason jars.
Remove the lid, you don't need it.
Look for the burrows of the mole crickets.
Carefully expose this.
Dig the mason jars here at ground level.
The opening should be flush with the surface of the earth.
Place a narrow board over the opening.
Mole crickets orient themselves on such obstacles when running.
You run along the board and fall into the glass
Empty the glasses early in the morning.

You can release the captured animals in a suitable place - as far away from your garden as possible. Make sure to wear thick gardening gloves made of a solid material, as mole crickets can pinch painfully.

Tips

This method is particularly successful during the mating season between April and June, as the animals here are increasingly on the surface of the earth.

Dig up brood nests

In the event of a strong infestation, it can make sense to dig up and remove the breeding nests of the mole crickets. This measure is particularly effective in June, when the animals have eggs or the young larvae have hatched from them. And that's how it works:

Examine the animals' burial tunnels.
Dig up the underground construction at a vertical junction.
There is probably a brood nest at about 30 centimeters deep.
Dig these out with a spade.
Discard the adult animals inside, as well as the eggs and larvae.

Use of nematodes

Another very effective method of combating mole crickets are nematodes of the species Steinernema Carpocapsae. These are tiny roundworms that infect the adult pests and introduce deadly bacteria into their bloodstream. With the help of these biological pest fighters, around 60 to 80 percent of the mole cricket population can be effectively eliminated. But be careful: the eggs and larvae are not attacked, which is why other adults can develop from them. It is therefore advisable to repeat the application every year.

The best time to spread the nematodes is between April and the beginning of June at the latest. At this point, the mole crickets have usually not yet laid eggs. In greenhouses or cold frames, you can spread the roundworms about six weeks earlier, provided the soil temperature is at least twelve degrees Celsius. If it is too cold, the beneficial insects die and cannot do their job.

Application of nematodes

You can get nematodes in gardening shops or on the Internet. Together with the animals, you will receive detailed instructions on how to use them, which you should absolutely adhere to. Mix the roundworms in a watering can with lukewarm water so that you can use a watering attachment to spread them over the infested area over a large area. Since nematodes are very sensitive to UV light, it makes sense to spread them when the sky is overcast or in the early evening hours.

Digression

Mole crickets are an endangered species

Since mole crickets have been massively fought over centuries and also have an extremely long larval period for the insect kingdom, the European species is now considered to be endangered and is therefore in category 2 of the red list. Other species of the genus are also considered endangered or even threatened with extinction. Despite this classification, mole crickets are not protected in Germany. With this they can be caught and killed. For reasons of species protection, however, it makes sense to catch the animals alive and release them again at a suitable location.

Are there any effective home remedies for mole crickets?

Many an “old hand” when it comes to gardening advises you to simply finish off the mole crickets with old cooking oil or butyric acid. To do this, pour about a tablespoon of oil into a vertical passage, followed by about 250 milliliters of water. In fact, this method is quite effective because both the larvae and the eggs die. The adult animals come to the surface and can be collected there without any problems.

Home remedies have disadvantages

The disadvantage of this method, however, is that edible oil and butyric acid remain in the soil, are not broken down there and thus also have negative effects on the soil quality and the groundwater. Experience has shown that such an admixture does not particularly benefit the plants growing on such a soil, which then simply take care of or even perish. The same applies to “household remedies” such as kerosene (or rags soaked with kerosene), alcohol, dishwashing detergent, etc.

It is also sometimes advised to dig the passage area about 60 centimeters deep, fill in horse manure and fill the hole again. However, this method has no effect at all against mole crickets, as these then simply dig other, new tunnels. Thus, the horse manure is only suitable as an organic fertilizer for the vegetable garden.

Better not to use home remedies

In summary, it can be said that you should keep your hands off “tried and tested” home remedies, as they either cause further damage unintentionally or are not effective at all. Better to use really effective methods right away, such as the nematodes presented here.

frequently asked Questions

Can mole crickets fly?

The very busy mole cricket not only digs meter-long corridors under the surface of the earth at night, but is also otherwise very agile: The animals can swim, even dive, and fly very well. However, flying mole crickets can only be observed during the mating season in May and June, when the females are looking for a male partner. Otherwise, most of the animals live underground. Incidentally, only the females fly, while the males stay in one place and emit a call. This noise sounds like a low whirring sound and can also be heard by humans.

Are mole crickets poisonous?

Quite a few gardeners - and also anglers, because the animals were and are often used as bait when fishing for catfish - have already had unpleasant experiences with the mole cricket: They can pinch badly when threatened (e.g. because you hold them in your hand). But don't worry: Mole crickets are neither poisonous nor do they give off any toxins. Also, if your dog should ever eat such an animal, you need not worry. However, you should not pick up the animals with your bare hand, instead wear sturdy gardening gloves: This will avoid painful pinching.

Are mole crickets dangerous?

Male mole crickets in particular have fierce battles among themselves during the mating season. However, the insects are absolutely harmless to humans and pets - and rarely seen, because with the slightest shock they retreat from the surface of the earth into the ground and flee.

How old can a mole cricket get?

Mole crickets are comparatively old: the animals go through various larval and molting stages in the first year, but are only fully developed in late summer / autumn of the following year. At this point in time, they are still not sexually mature, but will reach fertility again in the next year - that is, a full two years after hatching from the egg. Then the animals live for about another year, so that mole crickets have a total life expectancy of about three years - provided they do not fall victim to one of their numerous predators beforehand.

Mole, vole or mole cricket - who is digging up my garden?

If the garden plants wilt for no apparent reason, there could be various reasons. The mole is quite easy to recognize by its characteristic mound of earth, whereby this furry fellow prefers to feed on grubs and beetles - and not on roots and tubers. They are on the menu of the vole, which is a vegetarian and only feeds on plants. The mole cricket, on the other hand, only occasionally nibbles on tubers and roots, because it prefers to eat insects and their larvae. Nevertheless, if there is a strong infestation, there are traces of eating on carrots, potatoes and the like - the sheer lack of food tempts the animals to look for vegetable sources of food. However, the brisk digging activity means that the plants die off without being nibbled.

My crossword puzzle asks for the southern German word for mole cricket (with five letters). What's the solution?

Quite simply: In southern Germany, the animals that are found there far more frequently than in northern Germany are often referred to as “Werre” (plural is “Werren”). This solution is the right one for the crossword puzzle. In addition, mole crickets are also called “dwarfs” in some places. In Switzerland they are known under the name “Halbteufel”, in Austria they are known as “G'schwer”.

Tips

The biennial cruciferous milkweed (lat. Euphorbia lathyris), which is best planted / sown in a partially shaded spot in the garden, is said to have a deterrent effect on both mole crickets and voles.