The marmorated stink bug attacks garden fruit, boldly invades the house and pollutes the air. The large, fearsome bugs have been on the rise in Europe for several years and are causing significant crop losses. Investigations into the introduced harmful organism are in full swing. This guide highlights the current knowledge about stink bugs with tips for hobby gardens and living spaces.
What is a marmorated stink bug?
The beetle has the marbled stink bug, thanks to its shape and ringed antennae. Its food is the sap of plant parts. This beetle can cause 100 percent crop loss. They can even enter the buildings and emit a foul smell.
- The marbled stink bug is 15 mm long, ocher marbled and has white-black ringed antennae.
- The stink bug is harmful to fruit and leaves because it sucks out the plant sap. The resulting necrosis and deformities make fruits inedible.
- There are currently no control agents. Because the pests stink on contact, they are caught with a glass and carried out of the house.
Marbled stink bug portrait – profile
The marmorated stink bug is better known as the stink bug
For many hobby gardeners, the marmorated stink bug is still a blank slate. Loud media complaints from fruit growers in European infested areas, such as Switzerland and Liechtenstein, are raising alarm bells. In the course of an explosive multiplication and spread, the appearance of the unfriendly newcomer in the garden and house should be known. The following overview summarizes the criteria by which you can recognize a stink beetle:
| Marbled Stink Bug | |
|---|---|
| Body length | 12-17 mm |
| Body shape | flattened leaf-shaped |
| color | ochre-marbled with black dots |
| Wings | crystal clear with vertical stripes |
| Legs | ochre-colored, six-legged |
| Bottom | pale yellow, black dots on the sides |
| scientific name | Halyomorpha halys |
| Origin | East Asia |
| Common names | Stink beetle, stink bug |
Has this profile aroused your interest in more in-depth information? Then please read on. Important questions about appearance and properties receive a comprehensible answer below based on current findings (as of May 2020):
Are there any special identifying features?
The striking identifying feature of a marmorated stink bug is the long antennae on its head. These are made up of five segments with a dark base color and white ringlets. A black and white spot pattern on the edge of the rear half of the leaf-shaped body is characteristic. At the rear end of the body is the thin-skinned, transparent part of the wings, characterized by black lines. Furthermore, between the wings you can see a label with a row of several orange calluses. This series of dots removes any remaining doubts about species affiliation.
What makes marmorated stink bugs so dangerous?
The stink bug can cause devastating damage to horticulture
The marmorated stink bug targets more than 300 host plants worldwide, including more than 150 different plant species in Europe. The plant suckers cause the greatest damage to fruit crops, with crop losses of up to 100 percent. Fruit growers and amateur gardeners are helpless against the introduced harmful organism. The tendency of the winged invaders to invade houses and apartments to hibernate is not dangerous, but extremely annoying. If you get too close to the pests, they give off a bad smell.
How do stink bugs live and reproduce?
Stink bugs overwinter as adult insects, preferably in a protected, heated environment. When the thermometer exceeds 10 degrees in spring, stink bugs rub their hibernation out of their compound eyes and become active. Famished, they look for suitable host plants in order to fortify themselves on plant sap for a few weeks. The mating season begins in mid-May. Mated females lay the eggs in small packages on the undersides of leaves. Amazingly, there are usually exactly 28 eggs in each clutch. The female bugs lay several egg packages until July, producing up to 450 offspring per season.
The larvae hatch a few days after laying their eggs. One larva is born as a nymph, an incompletely developed, black and yellow mini stink bug. By mid/late July, baby bugs go through a total of 5 developmental stages. Within six to seven weeks after hatching, the first generation is already sexually mature and takes care of the production of a second generation. Both generations feed on their host plants well into the fall. When temperatures drop, marmorated stink bugs seek suitable winter quarters.
Which plants are threatened?
Even beans are attacked by the stink bug
The marmorated stink bug has a large appetite and is not particularly picky. Their food spectrum is correspondingly broad. Scientists speak of a polyphagous insect species, which literally means a heavy eater. The following plant species suffer the greatest damage:
- Main hosts fruit trees: apple, pear, blackberry, raspberry, cherry, nectarine, peach, wine, citrus fruits
- Arable crops: corn, asparagus, beans, soy, potatoes
- Bluebell tree (Paulownia tomentosa)
- Mountain ash (Sorbus aucuparia)
- God's Tree (Ailanthus altissima)
- Virgin vine (Parthenocissus)
- Cherry laurel (Prunus laurocerasus)
- Mahonia (Mahonia)
- Buddleia (Buddleja davidii)
- Trumpet tree (Catalpa)
Fruit vegetables are also on the diet of plant suckers, especially tomatoes, cucumbers and peppers. According to current knowledge, the pests initially appear in fruit cultivation. Once the fruit trees have been harvested, the hungry bug squad moves on to the vegetable and ornamental plant beds. If the temperatures are still pleasant in autumn when the nuts ripen, the pests do not spurn this food supply.
Why do marmorated stink bugs stink?
The marbled stink bug has a secretion on board to defend itself against enemies. In threatening situations, the liquid is sprayed and attacks our sense of smell with a repellent stench. The Asian stink bug species owes its second names stink beetle and stink bug to this fact. Any attempt to combat or even kill a stink bug in the house using harsh methods will turn the pest into a six-legged stink bomb.
Is the stink bug poisonous?
The defensive secretion of a marmorated stink bug emits an unpleasant smell. Stink beetles do not pose a he alth risk to people or pets. As part of the sucking activity on fruit and plant leaves, specific enzymes enter the plant tissue through saliva, causing necrosis, hardening and deformation. Scientists suspect that mold spores and pathogens get into the host plants at the same time. Subsequent consumption of affected fruits could have a serious impact on the stomach of a sensitive person. There is currently a lack of medical-scientific evidence regarding this thesis.
Can marmorated stink bugs bite?
Marbled stink bugs neither bite nor are they poisonous
Stink bugs have a spike-shaped mouthpart. The insects use this proboscis to pierce fruit and leaves in order to suck up the plant sap. Unlike the distantly related bed bugs and other pests, the mouthpart of a marmorated stink bug is not designed to bite into human or plant epidermis.
How did the marmorated stink bug come to Germany?
The marmorated stink bug is native to East Asia, primarily in East China, Japan and Korea. At the beginning of the new millennium, the pest was introduced to North America and has spread invasively. The gateway to Europe in 2007 was Switzerland. Here the stink bug landed in Zurich as a stowaway with a delivery of roof tiles from China. From here the winged invaders made their way through Europe. In Germany, the first discoveries were reported on Lake Constance in 2011. The conquest lasted almost 6 years as far as the Stuttgart area. Since then, the invasive spread has continued unstoppably in all directions, fueled by increasing global warming.
Asiatische Stinkwanze plagt badische Landwirte I Landesschau Baden-Württemberg
Tip
The marmorated stink bug is not the only new species of bug from distant lands. As a result of global warming, the green rice bug (Nezara viridula) from East Africa has discovered the mild winter regions of Germany. The bright green bug's diet includes all kinds of vegetable plants.
Can you fight the marmorated stink bug?
Investigations into effective control methods against marmorated stink bugs are still in their infancy. 2017 was the first year in Germany with a correspondingly high number of pests, as an approach for well-founded research. The focus is on biological and physical strategies, entirely in the spirit of nature and environmental protection. Hobby gardeners will have to be patient until practical and promising findings are available.
European predators urgently wanted
The marmorated stink bug has no enemies here, which is why it multiplies massively unhindered
In its Asian distribution area, the marmorated stink bug is successfully controlled with the samurai wasp. This is a parasitic wasp that parasitizes bedbug eggs. Female parasitic wasps lay their own eggs directly into a stink bug egg. Hatched wasp larvae eat bug eggs from the inside out and thus prevent their development.
The parasitic wasp method is familiar to hobby gardeners in Germany as a biological control agent against lice of all kinds. Researchers in Switzerland are investigating whether there is a species among the European parasitic wasps that can be used to combat stink bugs. Other potential predators are being researched, such as predatory insects or spiders. The Eureka moment hasn't happened yet.
A simple solution would be to import the samurai wasp and unleash it on the introduced stink bugs. However, our experiences with other beneficial insect imports have made us more aware of the associated risks. In the 1980s, Asian ladybird larvae (Harmonia axyridis) were introduced to Germany as beneficial insects against aphids. Since then, the aggressive beetles have massively displaced native two-spot and seven-spot ladybirds.
Insecticides are not very effective
In the USA, farmers and amateur gardeners have been struggling with marmorated stink bugs for some time. This results in a greater we alth of experience regarding effective control agents. Entire fields there were sprayed with chemical insecticides. The result was a deception. Immediately after application, thousands of stink bugs lay on the ground. After a few hours, the hardened insects picked themselves up again and happily continued their meal.
Various, highly potent poisons are effective against stink beetles. However, no one wants to eat fruits and vegetables that have been sprayed with pyrethroids, neonicotinoids and other chemical clubs.
Excursus
Marbled Stink Bug – Please Report Find
In order to get an overview of the spread of marmorated stink bugs, plant protection and agricultural authorities are asking for the public's help. An informal report of accidental finds in the garden, on the balcony or in the house is helpful. Ideally, you should take a photo of the bug with high resolution and send the image to the responsible authority by email, stating the location where it was found. You can find the addresses on the website of the respective State Office for Agriculture or by calling the public order office. There is currently no obligation to report, as is the case with rats.
Marbled stink bug in the house – what to do?
Marbled stink bugs in the house should be removed carefully so that they do not release their stinky secretions
Marbled stink bugs prefer to spend the warm season in the garden. There the beasts fill their bellies and devote themselves to reproducing. In late summer, stink beetles can be discovered on house facades exposed to the sun, where they can enjoy extensive sunbathing. This changes suddenly as soon as temperatures fall below 10 degrees. Now the Asian bugs are looking for a suitable winter quarters and boldly invade your house and apartment.
Due to the lack of effective control agents, there are currently few options for getting rid of the pests without polluting your own four walls with a horrible smell. However, you do not have to tolerate a brazen annexation of your apartment by uninvited guests. As a preventive measure, fly nets on windows and doors ward off a bedbug invasion. This is what you can do to combat marmorated stink bugs in your house:
Glass Method
Arm yourself with a piece of paper and a glass. Fold the paper once to improve stability. Place the glass over the crawling marmorated stink bug. The sedate insect is nowhere near as nimble as cockroaches and other winged nuisances in the house. If the stink bug is under the glass, slowly slide the paper underneath and move the intruder outside. Alternatively, let the stink bug crawl onto the paper and place the glass jar upside down over it.
Vacuum cleaner method
In order to get hold of a marmorated stink bug in hard-to-reach places, the vacuum cleaner has proven to be an effective tool for combating them in the house. Put a worn stocking over the exhaust air nozzle in advance to protect against the smell of secretions. Do not leave the vacuum cleaner bag in the device afterwards, but dispose of it with household waste.
In any case, please avoid trampling or crushing the insect. The fly swatter should therefore not be used. The pungent smell will remind you of your confrontation with the stink bug for days. Even premium room fragrances are a lost cause when faced with the foul stench of a dead stink bug.
Harmless doppelganger – risk of confusion
The gray garden bug, however, is completely harmless
The gray garden bug (Rhaphigaster nebulosa) is an innocent victim in the hunt for marmorated stink bugs. As a native species of stink bug, the garden bug looks very similar to the Asian invader and has a comparable lifestyle. Only a closer look reveals important differences and underlines their harmless status:
Appearance Gray Garden Bug
A gray-brown upper surface gives the 15 mm large insect its name. This subtle base color is interspersed with black and green speckles. The side edge of the abdomen is decorated with a border of alternating yellow and black spots. The row of dots is missing on the plate between the wings, which is an outstanding difference to the marmorated stink bug. The antennae are predominantly dark in color. A ringlet pattern can only be seen on the fourth and fifth antenna links. The gray garden bug is distinctively marked with black dots on its underside. In contrast, the stink bug usually has no dotting at this point or a few spots on the outer edge.
Occurrence and way of life
The native stink bug species is widespread in large parts of Europe. Gray garden bugs are diurnal and love warmth. With only one generation per year, the insects are far from experiencing explosive reproduction like their Asian counterparts. A female places a maximum of 40 eggs on the undersides of the leaves of various plants. That's just a fraction of the up to 450 eggs of a marmorated stink bug. The menu includes the juices of some deciduous trees, which does not cause any serious damage.
Fadly, gray garden bugs search in droves in late autumn for a protected place to overwinter. The associated short-term mass appearance on house walls is often misinterpreted as a marmorated stink bug infestation.
Fighting superfluous
Gray garden bugs like to overwinter in human buildings. When the winter sun shines in, the insects become active and fly against window panes. The local winter guests are not dangerous; they are more of a nuisance. The harmless image is tarnished by a smelly defensive secretion that endangered garden bugs secrete. Ideally, the window is opened to release the insect into the wild.
Frequently asked questions
Can marmorated stink bugs fly?
The marmorated stink bug can fly very well
The marmorated stink bug has a fully developed pair of wings and can fly well. Of course, you are not physically fit enough for longer distances. The stink bug travels long distances as a stowaway in transport crates, packaging, airplanes, ships and vehicles.
What does a stink bug larva look like?
During its developmental stages, the larva of a marmorated stink bug repeatedly changes its appearance. In the first larval instar the nymph is colored red-orange. From the second stage onwards, the baby bugs can be recognized by black-grey and black-white markings on their legs and side thorns in the front chest area. In the last larval stage, the first wing attachments appear on the dark brown body.
What damage does the marmorated stink bug cause?
Apple trees are at the top of the menu. Suction damage to the apples can be recognized as dark, sunken spots on the peel. Brown spots form underneath the shell. If apples that are ready to be harvested are affected, the proboscis causes dark, necrotic damage to the pulp, which sometimes only becomes apparent during winter storage. Constrictions and deformations on fruits are typical developmental disorders caused by stink bugs. In contrast, damage to vegetables and fruit crops reveals itself as light, whitish, spongy blemishes. After some time, brownish discoloration appears. Suction damage to leaves causes deformation, drying and premature leaf fall.
How can you prevent marmorated stink bugs in the garden?
Marbled stink bugs overwinter in populated areas. The pests fly from their winter quarters to the host plants in spring. For this reason, experts recommend netting endangered plants as a preventive measure. This effectively prevents entry. A negative side effect that should not be overlooked is that the protective nets also prevent access to birds, bees, butterflies and other beneficial insects. Experts therefore advise against completely netting entire orchards. The effort can be worthwhile for individual trees or bushes.
Tip
Marbled stink bugs are eager for sweet fruit and plant juices. Sour aroma, on the other hand, is anathema to the pests. From late summer onwards, rub all window and door frames regularly with vinegar to scare away stink bugs that approach the house in search of winter quarters. As a positive side effect, you can use this home remedy to ward off annoying mosquitoes and fruit flies.
