The marbled stink bug lays hands on garden fruit, cheekily invades the house and pollutes the air. In Europe, the large, frightening bugs have been on the rise for several years, causing significant crop losses. Investigations into the introduced harmful organism are in full swing. This guide highlights what is known about stink bugs with tips for hobby gardens and living spaces.

The marbled stink bug deals great damage

Table of Contents

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  1. the essentials in brief
  2. Marbled Stink Bug Wanted Poster
  3. Fight marbled stink bug?
  4. Stink bug in the house
  5. Harmless doppelganger risk of confusion
  6. frequently asked Questions

    7. the essentials in brief

    • The marbled stink bug is 15 mm long, marbled ocher and has white and black ringed antennae.
    • The stink bug is harmful to fruit and leaves because it sucks the plant sap. The resulting necrosis and crippling make fruit inedible.
    • So far there are no means of combating it. Because the pests stink on contact, they are caught in a jar and carried out of the house.

    Portrait of a marbled stink bug - wanted poster

    The marbled stink bug is better known as the stink bug

    For many hobby gardeners, the marbled stink bug is still a blank slate. Loud media complaints from fruit growers in European infested areas, such as Switzerland and Liechtenstein, are ringing 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 12-17mm
    body shape leaf-shaped flattened
    color ocher marbled with black dots
    wing crystal clear with longitudinal stripes
    legs ocher, six-legged
    bottom pale yellow, dotted with black on the sides
    scientific name Halyomorpha halys
    origin East Asia
    trivial names Stink bug, stink bug

    Has this profile aroused your interest in more detailed information? Then please read on. Important questions about appearance and properties are given a comprehensible answer based on the current findings (as of May 2022):

    Are there any special identifying features?

    A distinctive feature of a marbled stink bug are the long antennae on the head. These are composed of five segments with a dark base color and white ringlets. A characteristic feature is a black and white spot drawing on the edge of the rear half of the leaf-shaped body. At the rear end of the body is the thin-skinned, transparent part of the wings, marked by black lines. Furthermore, between the wings there is a shield with a row of several orange calluses. This row of dots removes the last doubts about the species affiliation.

    What makes marbled stink bugs so dangerous?

    The stink bug can wreak havoc in horticulture

    The marbled stink bug has more than 300 host plants in its sights worldwide, including more than 150 different plant species in Europe. The plant suckers cause the greatest damage in orchards, with harvest losses of up to 100 percent. Fruit growers and hobby gardeners are helpless at the mercy of the introduced harmful organism. Not dangerous, but extremely annoying is the tendency of the winged invaders to enter houses and apartments in order to hibernate. If you get too close to the pests, they give off a foul smell.

    How do stink bugs live and reproduce?

    Stink bugs overwinter as adult insects, preferably in a sheltered, heated environment. When the thermometer rises above 10 degrees in spring, stink bugs rub their compound eyes out of hibernation and become active. Starving, they keep an eye out for suitable host plants in order to strengthen themselves on the plant sap for a few weeks. The mating season begins in mid-May. Mating females lay eggs in small clusters on the underside of leaves. Amazingly, there are usually exactly 28 eggs in each clutch. Until July, the lady bugs place several egg packages and thus have up to 450 offspring per season.

    The larvae hatch a few days after the eggs are laid. A larva is born as a nymph, an immature, black and yellow mini stink bug. By the middle/end of July, baby bugs go through a total of 5 stages of development. 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 autumn. When the temperatures drop, the marbled stink bugs look for a suitable winter quarters.

    Which plants are threatened?

    Even beans are attacked by the stink bug

    The marbled stink bug has a big appetite and is not particularly picky. Their diet is correspondingly broad. Scientists speak of a polyphagous insect species, which literally means a lot of eaters. The following plant species suffered the greatest damage:

    • Main hosts fruit trees: apple, pear, blackberry, raspberry, cherry, nectarine, peach, vine, citrus
    • Arable crops: corn, asparagus, beans, soybeans, potatoes
    • Bluebell tree (Paulownia tomentosa)
    • Rowan (Sorbus aucuparia)
    • Tree of Heaven (Ailanthus altissima)
    • Maidenhair Vine (Parthenocissus)
    • Cherry laurel (Prunus laurocerasus)
    • Oregon Grape (Mahonia)
    • Summer lilac (Buddleja davidii)
    • Trumpet Tree (Catalpa)

    Fruit vegetables are also on the menu of plant suckers, especially tomatoes, cucumbers and peppers. According to current knowledge, the pests initially romp about in fruit growing. Once the fruit trees have been harvested, the hungry squadron of bugs moves on to the vegetable and ornamental plant beds. If temperatures are still pleasant in autumn when the nuts are ripening, the pests do not shy away from this food supply.

    Why do marbled stink bugs smell?

    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 repulsive stench. The Asian stink bug species owes its middle name stink beetle and stink bug to this circumstance. Any attempt to fight or even kill a stink bug in the house with ruthless methods turns the pest into a six-legged stink bomb.

    Is the stink bug poisonous?

    The defense secretion of a marbled stink bug gives off an unpleasant smell. Stink bugs do not pose a health risk to humans or pets. As part of the sucking activity on fruit and plant leaves, specific enzymes enter the plant tissue with the 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 fruit could cause severe stomach upset in a sensitive individual. There is currently no medical-scientific proof of this thesis.

    Can marbled stink bugs bite?

    Marbled stink bugs cannot 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 vermin, a marbled stink bug's mouthpart is not designed to bite human or plant epidermis.

    How did the marbled stink bug come to Germany?

    The marbled stink bug is native to East Asia, mainly in East China, Japan and Korea. The pest was introduced to North America at the beginning of the new millennium 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 across Europe. In Germany, the first finds were reported at Lake Constance in 2011. The conquest took almost 6 years to reach the Stuttgart area. Since then, the invasive spread has continued unabated in all directions, fueled by increasing global warming.

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    The marbled stink bug is not the only new species of bug from distant lands. In the course of global warming, the green rice bug (Nezara viridula) from East Africa discovered the regions of Germany with mild winters. Vegetables of all kinds are on the menu of the bright green bug.

    Can you fight the marbled stink bug?

    Investigations into effective control methods against marbled stink bugs are still in their infancy. 2022 was the first year in Germany with a correspondingly high incidence of pests, as a starting point for well-founded research. The focus is on biological and physical strategies, 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 marbled stink bug has no enemies with us, which is why it multiplies massively unhindered

    In its Asian distribution area, the marbled stink bug is successfully combated with the samurai wasp. It is a parasitic wasp that parasitizes bug eggs. Female parasitic wasps lay their own eggs directly in a stink bug egg. Hatched wasp larvae eat bug eggs from the inside 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 (€22.99) that can be used to fight stink bugs. Other potential predators are being researched, such as predatory insects or spiders. The eureka moment hasn't materialized so far.

    A simple solution would be to import the samurai wasp and let loose on the introduced stink bugs. However, experiences with other beneficial insect imports have made us 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 United States, marbled stink bugs have been a problem for farmers and home gardeners for some time. This results in a greater wealth of experience with regard to effective control agents. Whole fields were sprayed there with chemical insecticides. The result was a sham. Immediately after the 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 toxins are effective against stink beetles. However, no one likes to eat fruits and vegetables that have been sprayed with pyrethroids, neonicotinoids and other chemical bludgeons.

    digression

    Marbled stink bug - please report find

    In order to get an overview of the spread of marbled stink bugs, authorities for plant protection and agriculture are asking for the help of the population. An informal report of accidental finds in the garden, on the balcony or in the house is already helpful. Ideally, you should take a high-resolution photograph of the bug and send the picture by e-mail to the responsible authority, stating where it was found. You can look up the addresses on the website of the respective state institute for agriculture or by calling the regulatory 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 carefully removed so that they do not give off 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 reproduction. In late summer, stink beetles can be spotted on sun-exposed house facades to enjoy extensive sunbathing. That changes abruptly as soon as the temperatures fall below the 10 degree mark. Now the Asian bugs are looking for a suitable winter quarters and boldly march into the house and apartment.

    In the absence of effective control agents, there have so far been 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. Fly nets on windows and doors prevent a bug invasion. What you can do against marbled stink bugs in the house:

    glass method

    Arm yourself with a piece of paper and a glass. Fold the paper once to improve stability. Put the glass over the crawling marbled stink bug. The portly insect is not nearly as agile as cockroaches and other winged nuisances in the house. If the stink bug is under the glass, slowly slide the paper underneath and kick the intruder out. 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 marbled stink bug in hard-to-reach places, the vacuum cleaner has proven to be a tried and tested tool for combating it in the house. Pull a worn-out stocking over the exhaust air nozzle beforehand to protect against the smell of secretion. Do not leave the vacuum cleaner bag in the device afterwards, but dispose of it with the household waste.

    In any case, please avoid stepping or crushing the insect. The fly swatter should therefore not be used. The pungent smell will remind you of the confrontation with the stink bug for days. Even premium room fragrances are lost to the foul stench of a slain stink bug.

    Harmless doppelganger - risk of confusion

    The gray garden bug, on the other hand, is completely harmless

    The gray garden bug (Rhaphigaster nebulosa) is an innocent victim in the hunt for marbled stink bugs. As a native stink bug species, the garden bug looks confusingly similar to the Asian invader and maintains a comparable lifestyle. Only a closer look reveals important differences and underpins their harmless status:

    Appearance Gray garden bug

    A grey-brown upper side gives the 15 mm insect its name. This subtle base color is interspersed with black and green speckles. The lateral edge of the abdomen is decorated with a border of alternating yellow and black spots. The row of dots is missing on the shield between the wings, as a prominent difference to the marbled stink bug. The tentacles are predominantly dark in color. A ringed pattern can only be seen on the fourth and fifth antenna element. On the underside, the gray garden bug is marked with black dots. In contrast, the stink bug usually has no punctuation 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 the explosive reproduction of their Asian counterparts. A female places a maximum of 40 eggs on the underside of the leaves of various plants. This is only a fraction of up to 450 eggs of a marbled stink bug. The juices of some deciduous trees are on the menu, which does not cause any serious damage.

    Fatally, gray garden bugs flock in late autumn looking for a sheltered place to overwinter. The associated, short-term mass occurrence on house walls is often misinterpreted as a marbled stink bug plague.

    combat superfluous

    Gray garden bugs like to hibernate 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, but rather to be rated as nuisances. The harmless image is scratched by a stinking weir secretion that endangered garden bugs secrete. Ideally, the window is opened to release the insect into the wild.

    frequently asked Questions

    Can marbled stink bugs fly?

    The marbled stink bug can fly very well

    The marbled stink bug has a fully developed pair of wings and can fly well. Of course, the condition is not sufficient 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 the course of its developmental stages, the larva of a marbled stink bug repeatedly changes its appearance. In the first larval stage, the nymph is red-orange in color.From the second stage, the baby bugs can be recognized by the black and gray and black and white markings on their legs and lateral thorns in the front chest area. In the last larval stage, the first wing attachments appear on the dark brown body.

    What kind of damage does the marbled stink bug cause?

    Apple trees are at the top of the menu. Sucking damage to the apples can be seen as dark, sunken spots on the skin. Brown spots form below the shell. If apples that are ready to be harvested are affected, the proboscis causes dark, necrotic damage to the flesh of the fruit, 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 fruiting vegetables manifests as light-colored, whitish, spongy blemishes. After some time, brownish discolorations appear. Suction damage to leaves causes deformation, desiccation and premature leaf fall.

    How to prevent marbled stink bugs in the garden?

    Marbled stink bugs overwinter in populated areas. From their winter quarters, the pests fly to the host plants in spring. For this reason, experts recommend wetting endangered plants as a preventive measure. This effectively prevents entry. As a negative side effect, it should not be overlooked that the safety nets also deny access to birds, bees, butterflies and other beneficial insects. Experts therefore advise against a total netting of entire orchards. The effort can be worthwhile for individual trees or shrubs.

    tips

    Marbled stink bugs crave 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 off stink bugs that approach the house in search of winter quarters. As a positive side effect, you can also use this home remedy to ward off annoying mosquitoes and fruit flies.

Category:

Animals in the garden