The primitive-looking mole cricket is a rare guest in the garden. As a rule, it does not cause any damage. Only when the population becomes too large does it literally dig up the garden, destroying seeds and young plants. This is what you can do against the animals.
- The mole cricket is a locust, but lives largely underground and creates tunnel systems that are meter long and up to four meters deep.
- The insect feeds almost exclusively on maggots, worms, eggs and other animal food, which is why it is actually classified as a beneficial insect. The claim that mole crickets also eat roots and tubers is simply false.
- However, if the population in the garden is too large, the animals can still cause considerable damage through their heavy digging activity.
- The best way to combat them is 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 lifestyle of the mole cricket
The mole cricket has its name for a reason: its large digging shovels and its underground lifestyle are strongly reminiscent of the mole, and the insect also belongs to the grasshopper family (Latin: Orthoptera), resembles a large cricket and also produces completely 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
The mole cricket with its large shovels lives up to its name
- Species: European or Common Mole Cricket
- Latin name: Gryllotalpa gryllotalpa
- Popular names: Werre, G’schwer (Austria), Zwergel, Halbteufel (Switzerland)
- Class: Insects (lat. Insecta)
- Subclass: Flying Insects
- Order: Grasshoppers (lat. Orthoptera)
- Subordination: long-feeling terror (lat. Ensifera)
- Habitat: in loose, preferably sandy to loamy soil, often near water and in meadows, lawns or in gardens
- Occurrence: Europe, North Africa, Western 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 primitively cancerous-looking animals, which are up to ten centimeters long, appear clumsy and massive. Especially when such an insect buzzes around the garden during the mating season, many a garden owner becomes dizzy.
But mole crickets are completely harmless. They also spend most of their lives underground in the ground, which is why they are physically perfectly adapted to this life. Its body is protected by a thick chitinous shell, and the insect uses its characteristic large digging shovels to dig its many-meter-long tunnels.
- Size: usually between four and six centimeters, in exceptional cases larger
- Coloring: light to dark brown, matt shiny, bottom often lighter than top
- Physical structure: strong, primitive, body is covered with fine hair
- Head: large, well protected with chitinous shell
- Legs: four-jointed front legs shaped like digging shovels, inconspicuous – – – – –Hind legs: (no jumping legs like others Locust species)
- Wings: short forewings, longer hindwings protruding over the abdomen
- Special features: produces a loud, buzzing noise with its wings during the summer months
You can hear what the chirping of mole crickets sounds like in this article:
Although mole crickets are grasshoppers, unlike their relatives they cannot jump. Although the animals are very loud and can hear very well themselves, they primarily perceive the sounds of their own species. The compound eyes typical of the species are also missing.
Occurrence and distribution
The European version of the mole cricket has become rare, even if some troubled gardeners find this hard to believe. The main reason for this is the strict control of animals in the garden and in agriculture, as the insects often settle in compost and manure 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 native to almost all parts of the world, with most populations found in the Mediterranean region. In Germany, mole crickets are mainly found in southwest Germany, but are almost unknown in the north.
Lifestyle and reproduction
Mole crickets spend two years in the larval stage
Mole crickets create meter-long tunnel systems in the garden, which primarily consist of channels that run 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 deeper storage and feeding chambers as well as to the breeding chambers. While the individual passages are often no wider than about six centimeters, the chambers can be the size of a tennis ball or even a football. They are reinforced and secured with plant parts, which the animals press into the earth's walls with their solid shells. Mole crickets are very busy and dig up to 40 meters a day.
The mole cricket spends almost its entire life underground, only leaving its native habitat during the mating season between the beginning of May and mid-June. The nocturnal animals can only be seen in the evening and at night. Only the female animals can fly and in this way follow the mating calls of the male mole crickets. After mating, the female lays up to 1,000 eggs (but usually only between 100 and 300) in an underground breeding chamber, which she sticks to the cave walls. The eggs are guarded and cared for by the female, and 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 approximately 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 shed their skin three times in total until autumn.
- The larvae overwinter in the ground and molt a fourth time in spring.
- At this point they can move very quickly.
- In contrast to the adults, these larvae can still jump.
- At the end of July of the second year, the animals are already fully developed.
- However, sexual maturity does not occur until the following year.
Due to the long development time, a garden infested with mole crickets typically contains larvae and adults of all stages of development and age.
What does the mole cricket eat?
“Mole crickets don’t eat vegetables!”
It was previously thought that mole crickets prefer to eat roots. That's why the animals were massively persecuted. However, it is now known that the animals eat almost exclusively carnivorous food: their diet includes worms, maggots, larvae as well as insect and snail eggs. Only very rarely and when there is a severe shortage of food do mole crickets eat plant-based food in the form of roots and tubers. The damage that undoubtedly occurs in the garden is therefore less due to the animals' feeding than to the large-scale digging activity of the animals.
Excursus
Pest or beneficial?
Due to their strong preference for animal food, mole crickets cannot be clearly classified as garden pests. After all, the eager fellows destroy numerous pests such as grubs, snail eggs (which results in fewer hungry slugs), black weevils, etc. This means that the animals - as long as they do not appear in large numbers in one place - can even be valued as beneficial.
This is how you can recognize a mole cricket infestation
As a rule, you don't even notice whether the mole cricket feels comfortable in your garden. Usually there are only a few animals, whose population is kept low by their natural enemies - above all the mole. If the food supply is plentiful - i.e. the table is richly covered with maggots, larvae and eggs - mole crickets will not eat any plants. The typical damage pattern can only be seen when there is a severe infestation and there are not enough food animals:
- Feeding holes in radishes, potatoes and other tubers
- vegetable and ornamental plants that wilt primarily in spring
- troubled 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. Typically, older plants are quite well protected from the mole cricket, which is why, for example, in regions at risk, you should only plant early and strong vegetable plants in the bed. Voles, on the other hand, also nibble on the roots of older and larger plants. Mole crickets also do not throw up piles of dirt, which are typical for 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 actually welcome as pest killers. In this case, however, make sure to keep the number of Werren as low as possible with the help of their predators; catching and releasing live specimens is also a suitable way to limit them. However, if the infestation becomes too severe (for example due to a lack of predators) and the damage increases significantly, you will have to resort to heavier guns. Certain nematodes, for example, are very suitable for this.
Attract predators to the garden
Mole cricket infestations rarely explode because predators keep them low
Underground, the mole cricket basically only has one enemy: the mole. The furry loner not only competes with the insect in its habitat, but also ensures a smaller supply of food - after all, the mole also lives on animal food and therefore has the same menu as the Werre. On top of that, it is a real delicacy for moles and is therefore eaten with pleasure. This is not the only reason why you should not rush to drive moles out of the garden, even if the piles of earth are occasionally annoying. The little diggers do an excellent job of keeping garden pests at bay.
If the mole cricket comes to the surface, other garden residents 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 like to scratch and peck at 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 at seeds, seedlings and young plants or eat their fill of lettuce instead of mole crickets. But chickens are very suitable for keeping a lawn free of pests.
Otherwise - not only to keep the garden free of mole crickets, but also free of other pests - it is important to ensure that it is managed as close to nature as possible. This includes measures like these:
- no toxins in the garden
- d. H. no pesticides, herbicides, insecticides, fungicides etc.
- These also poison useful garden creatures.
- Set up or hang up bird feeders and incubators
- Build insect hotels in strategically and climatically good locations
- Create hiding places for larger animals: piles of stones and wood in a corner of the garden, e.g. B.
- prefer native plants in the garden
- especially lots of umbelliferous plants, these attract beneficial insects
In such a garden, plant protection measures are less often necessary because the biological balance is created and maintained in a completely natural way. Mole crickets have no chance of reproducing too much.
Tip
Digger wasps of the species Larra anathema also hunt mole crickets and were therefore introduced from their original 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.
Setting up traps
It is quite effective and animal-friendly, but it is also quite time-consuming to catch mole crickets. The best way to do this is as follows:
- Take several smooth-sided preserving jars.
- Remove the lid, you don't need it.
- Look for mole cricket burrows.
- Carefully expose them.
- Dig the preserving jars here at ground level.
- The opening should be flush with the ground surface.
- Place a narrow board over the opening.
- Mole crickets orientate themselves on such obstacles when running.
- They run along the board and fall into the glass
- Empty the glasses early in the morning.
You can release the caught animals in a suitable place - as far away from your garden as possible. Be sure to wear thick gardening gloves made of a sturdy material, as mole crickets can hurt painfully.
Tip
This method is particularly successful during the mating season between April and June, as the animals spend more time on the surface of the earth.
Dig up breeding nests
If there is a severe infestation, it may make sense to dig up and remove the mole cricket breeding nests. This measure is particularly effective in June, when the animals have eggs or the young larvae have already hatched from them. And this is how it works:
- Examine the animals' burrows.
- Dig up the underground structure at a vertical junction.
- There is probably a breeding nest about 30 centimeters deep.
- Dig these out with a spade.
- Dispose of the adults, eggs and larvae inside.
Use of nematodes
Nematodes kill mole crickets effectively but very painfully
Nematodes of the type Steinernema Carpocapsae are also a very effective method for combating mole crickets. These are tiny roundworms that attack the adult pests and introduce deadly bacteria into their bloodstream. With the help of these biological pest controllers, around 60 to 80 percent of the mole cricket population can be effectively eliminated. But be careful: the eggs and larvae are not affected, which is why further adults can develop from them. It is therefore advisable to repeat the application annually.
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 any eggs. You can also spread the nematodes about six weeks earlier in greenhouses or cold frames, provided the soil temperature is at least twelve degrees Celsius. If it is too cold, the beneficial insects die and cannot fulfill their task.
Application of nematodes
You can get nematodes from garden shops or online. Together with the animals you will receive detailed instructions on how to use them, which you should definitely adhere to. Mix the nematodes in a watering can with lukewarm water so that you can spread them over a large area over the infested area using a watering attachment. Since nematodes are very sensitive to UV light, it makes sense to apply them when the sky is overcast or in the early evening.
Excursus
Mole crickets are endangered species
Since mole crickets have been massively combated for centuries and also have an extremely long larval period for the insect kingdom, the European species is now considered highly endangered and is therefore in category 2 of the Red List. Other species in the genus are also considered endangered or even threatened with extinction. Despite this classification, mole crickets are not protected in Germany. This means they can be caught and killed. However, for reasons of species protection, it makes sense to catch the animals alive and release them again in a suitable place.
Are there effective home remedies for mole crickets?
Many “old hands” when it comes to gardening advise simply killing 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 adults come to the surface and can be easily collected there.
Home remedies have disadvantages
The disadvantage of this method, however, is that cooking oil and butyric acid remain in the soil, are not broken down there and therefore have negative effects on soil quality and groundwater. Experience has shown that such an admixture is not particularly good for the plants growing in such soil, as they then simply take care of or even die. The same applies to “home remedies” such as petroleum (or rags soaked in petroleum), alcohol, dishwashing liquid, etc.
It is also sometimes advised to dig up the passage area about 60 centimeters deep, fill in horse manure and fill the hole back up. However, this method has no effect at all against mole crickets, as they then simply dig other, new burrows. Horse manure is therefore only suitable as organic fertilizer for the vegetable garden.
It's better not to use home remedies
In summary, it can be said that you should stay away from “tried and tested” home remedies, as they either unintentionally cause further damage or are not even effective. It's better to use really effective methods straight away, such as the nematodes presented.
Frequently asked questions
Can mole crickets fly?
Mole crickets are true all-rounders
The very busy mole cricket not only digs meter-long tunnels under the earth's surface at night, but is also very mobile in other ways: the animals can also swim very well, even dive, and even fly. 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. By the way, only the females fly, while the males stay in one place and emit a call. This noise sounds like a deep buzzing and can also be heard by humans.
Are mole crickets poisonous?
Many gardeners - and also anglers, because the animals were and are often used as bait when catching catfish - have already had unpleasant experiences with the mole cricket: They can be strong when threatened (for example because you pick them up). pinch. But don't worry: mole crickets are neither poisonous nor do they release any toxins. Even if your dog eats one of these animals, you don't need to worry. However, you should not pick up the animals with your bare hand, but instead wear sturdy gardening gloves: This will avoid painful pinching.
Are mole crickets dangerous?
Male crickets in particular engage in sometimes violent fights with each other during the mating season. However, the insects are absolutely harmless to people and pets - and are rarely seen, because at the slightest shock they retreat from the surface into the ground and flee.
How old can a mole cricket live?
Mole crickets grow comparatively old: The animals go through various larval and molting stages in the first year, but are not fully developed until late summer / autumn of the following year. At this point they are still not sexually mature, but will reach reproductive capacity again the next year - a full two years after hatching from the egg. The animals then live for about another year, so that mole crickets have a total life expectancy of around three years - assuming 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 seem to be wilting for no reason, there could be various reasons behind it. The mole is easy to recognize by its characteristic mounds of dirt, although this furry fellow prefers to feed on grubs and beetles - and definitely not on roots and tubers. They are on the menu of the vole, which is a vegetarian and only eats plants. The mole cricket, on the other hand, only occasionally nibbles on tubers and roots; it prefers to eat insects and their larvae. Nevertheless, when there is a severe infestation, there are traces of eating on carrots, potatoes, etc. - the sheer lack of food leads the animals to look for plant-based food sources. However, the busy digging activity means that the plants die even if left unnibbled.
My crossword puzzle asks for the southern German word for mole cricket (with five letters). What is the solution?
Quite simple: In southern Germany, the animals that are much more common there 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 as “Halbteufel”, while in Austria they are known as “G’schwer”.
Tip
The two-year-old cross-leaved spurge (Latin: Euphorbia lathyris) is said to have a deterrent effect on both mole crickets and voles and is best planted/sown in a semi-shady location in the garden.