Everything About Brown Marmorated Stink Bugs （2018）

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Brown Marmorated Stink Bugs: Behaviour, Life-Cycle, and Agricultural Concerns

Brown Marmorated Stink Bugs: Behaviour, Life-Cycle, and Agricultural Concerns

A native of Japan, the Korean Peninsula, China, and Taiwan, brown marmorated stink bug is no longer a stranger to the farms and orchards of the United States of America. These bugs have a bad reputation for flooding the orchards when the fruits are ripe and ready for harvest. Though the bug is beautifully marked with blue, black, brown and grey markings, can it stink? And what can you do to deal with the havoc this tiny bug can cause in the fields and how to deal with the bug bite? Well, read along to learn more about brown marmorated stink bug, harmness of brown marmorated stink bug conducted to agriculture, and whether this harmless looking creature bites.

1. What is Brown Marmorated Stink Bug?

Before proceeding towards more complex questions, let us figure out why the term ‘marmorated’ is used. These bugs have been assigned the adjective “marmorated’ because their body is veined like marble. These intricate markings of various shades of blue, grey, copper, and off-white are unique to this specie accompanied by alternating bands on the antennae. Brown Marmorated Stink Bugs belong to the Pentatomidae family, which is, originally, a native of Japan, Taiwan, the Korean Peninsula, and China.

Brown marmorated stink bugs are tiny creatures. Their average size is 1.7 centimetres and they are equally broad. They look like any typical stink bugs with shield-like structure covering their slightly banded legs and stink gland, which is present between the two pairs of legs, below thorax.

To learn more about brown marmorated stink bugs, it is important to understand the behaviour they follow. Like any other stink bug, they use proboscis to pierce their target plant to suck and feed on them. This feeding on fruits and leaves leave grooves, dimples or necrotic deformities on them, resulting in seed loss, leaf stippling, and might also lead to the transfer of plant pathogens.

The only defence mechanism brown marmorated stink bugs follow is to stink. They have developed this ability to emit an odour, which, apparently, smells like coriander, in order to protect themselves from being eaten up by lizards, birds and other bigger insects. However, if you try to manhandle, or simply handle the bug, it will release the odour as its only defence mechanism.

2. The Life Cycle of Brown Marmorated Stink Bugs

Winters can be harsh upon the brown marmorated stink bugs but the adults overwinter by hiding in the warmer spaces which include decks of houses, warehouses, and other such buildings. During fall, they can be spotted hiding into soffits, around windows, under sidings, chimneys and any openings which are wide enough for them to survive the winter. During this period, they go into an inactive state, also known as hibernation. Though this hibernation doesn’t necessarily put them into an inactive state. The warmth inside the houses make them active again and they fly clumsily about the house around light fixtures and food. They emerge out of this sleep-like state once the winters are over and its spring all over again!

Brown marmorated stink bugs begin mating in the spring season, two weeks after they come out of hibernation. When ready to mate, the male sends vibrational signals and releases pheromones to attract the females, who in return send vibrational signals. This process of using vibrational signals to locate each other is common for all stink bugs. They mate several times every year. A female can lay up to 486 eggs in her lifetime. The eggs are incubated in the female body for 148 degree days and after that, they require 538 degree days to develop into adults. Degree days is the time period with suitable temperature and time for the growth of this insect. The eggs are laid beneath leaves in masses of 28 minuscule light-green eggs.

The nymphs stay close to the nesting area untill they do not develop into full-grown adults. This is important for the continuation of the life-cycle of brown marmorated stink bug because the nymphs are brightly coloured and can be spotted by birds or other attackers. The adults easily bled with the tree barks though. Brown marmorated stink bugs go through 5 stages as nymphs which ranges from 2.4 mm to 12 mm. they pose a greater threat to crops because they mate several time every year and, therefore, they produce several broods each year. The life cycle of brown marmorated stink bugs ends within 6-8 months.

Brown marmorated stink bug is a major agricultural threat, which can lead the crops of an entire region useless if infested.

3. Origin and Expansion of Brown Marmorated Stink Bugs in the World

Halyomorpha halys (Stål) or brown marmorated stink bug is recognised as a pest in the places of its origin. The term ‘pest, is generally used for insects which cause damage to crops. Brown marmorated stink bugs are known to feed upon food crops which can vary from cash crops, fruits, and regular grains. Though they haven’t caused much of a havoc in Japan, China, the Korean Peninsula and Taiwan, brown marmorated stink bugs have become a major concern for the farmers in North America. The bugs were accidentally introduced to the ecosystem of the continent and since then, they have been flooding the fields year after year.

What you didn’t know about brown marmorated stink bug is that, because it is the native of the region which comprises of Japan, Korea, China, and Taiwan, they have had enough time to do their research on the bug’s biological functioning. This study has helped these countries to figure out how they can deal with them. But, they’ve been discovered in North America only a couple of decades ago in the year 1998. Once to species was introduced to the environment, it took no time in expanding its population and it took no time in spreading in warehouses, homes, and office buildings. The brown marmorated stink bugs soon became a nuisance in the country.

One factor which contributed to the aforementioned rapid expansion of bug population was the abundance of food resources, which provided them with a clear ground to grow upon. By the year 2004, farm produce became threatened by these invasive creatures. In 2010, farms of the mid-Atlantic region were badly hit. Especially the ones growing peaches, apples, sweet corn, tomatoes, and peppers. Some of them a reported complete loss that year. And since then, the brown marmorated stink bug continues to haunt the production of fruit crops all season long.

Researches have shown that the 3 variants of the insect found in Northern America have been brought in from China. The ones found in the mid-Atlantic region and Canada, are less diverse and are said to have originated near Beijing, China. The variants found in the eastern regions of North America are from other parts of China which have been accidentally introduced to the region by the movement of individuals within the continent.

4. What Led to an Increase of Brown Marmorated Stink Bug Population in North America?

Though the brown marmorated stink bugs were accidentally introduced in Northern America, it isn’t always the case that a species establishes such a stronghold in the region by the mere introduction into the environment. The climate of the region turned out to be suitable for the insect to grow in, hence, it has now become an invasive species, growing in number day-by-day.

Along with an ideal climate for reproduction, the fact that the litter of a female brown marmorated stink bug can range from 400-500 eggs in a lifetime is also a major reason for their rapid population outburst. It doesn’t take a hatched egg to develop into an adult more than 35-45 regular days. And the adults copulate several times a year, making them capable enough of producing one successful generation every year in any climate. In the warmer states, there is no stopping them, as they can then produce several generations in a warmer year.

The rapid expansion of the Brown marmorated stink bug population has been a major concern for the authorities as well as the farmers. Harmness of the brown marmorated stink bugs conducted to agriculture only increases with this population growth. There are biologists working on how they can control the expanding population of brown marmorated stink bugs, but they have not yet discovered a way in which the environment can play a role in controlling their population. Neither are they able to limit their spread across more states. As the climate of more states will grow warmer because of the increasing global warming, it will give the brown marmorated stink bugs a greater ground to breed in.

5. Harmness of Brown Marmorated Stink Bug Conducted to Agriculture

The Eastern United States has been drastically hit by the increased population of the brown marmorated stink bugs as they feed upon food crops all-round the season, leaving the produce unfit for sale in the markets or for further processing.

It is not just the problems faced by the farmers in the United States but the infestation of the corn and soybean crops in Japan, China, Korea, and Taiwan is also a major concern for the farmers of the regions. It is difficult to

What you didn’t know about Brown marmorated stink bugs is that they feed upon a wide variety of plants including apples, Asian pears, cherries, corn, apricots, grapes, lima beans, peaches, soybeans, peppers, and tomatoes. We can say that brown marmorated stink bugs do not require a specific crop to feed upon, making their existence all the more dangerous. They feed upon plant fluids. In order to obtain their food, they pierce the plant tissues to suck the plant fluids out of them. Plants get their fluids from the soil and they are very important for a healthy produce. This loss of plant fluids due to the invasion of thousands of brown marmorated stink bugs at one go leads to:

Destruction and deformation of seeds. The new seeds are required to grow new plants and trees. Due to their destruction, there is more pressure on farmers to procure new seeds in addition to having had a damaged crop in the previous season.
Delayed plant maturation. As the plants lose a lot of fluids to the brown marmorated stink bugs, the lack of nutrients delay the maturation of the plants, which ultimately delays the entire harvest and the farmers suffer huge losses.
Increase in vulnerability to harmful pathogens. Plant pathogens are the microbes which cause diseases in plants. Brown marmorated stink bugs wander to various fields for food and while doing that they might get in contact with microbes of certain plant diseases which can prove fatal for the farm.
Another damage that they cause to the harvest is that while sucking the plant fluids, they inject their saliva into the fruit pulp, which ultimately leads to the rotting of the fruit.

Invasion of the brown marmorated stink bugs on a plant causes leaf destruction, scars or dimples on the surface of the fruit, and gives a mealy texture to the fruits and vegetables, which could have otherwise been a healthy harvest. Because of these damages caused by brown marmorated stink bugs, the farmers suffer huge losses. The rotten insides of the fruits and vegetables are usually identifiable by looking at their surface and, therefore, they become unsuitable for the market.

The case with corn and soybeans is a bit different. Usually, the bugs affect the corn kernels, leaving no indication of harm on the husk, it is after the harvest and the removal of the husk that the farmer realises that the crop has been infested by brown marmorated stink bugs. In case of soybeans also the pods remain intact whereas the beans inside the pods have been preyed upon. One of the effects that the soybean crop faces if it had been infected by the bugs is “stay green” effect, which makes the crop stay green for long, even after the unaffected crops die naturally.

6. Do Brown Marmorated Stink Bugs Bite or Cause Damage?

The brown marmorated stink bugs are not equipped to bite or cause damage to anyone. The physical structure of these bugs is not designed to attack or harm anyone, they are harmless creatures in that respect. The only defence mechanism they can rely upon is their ability to emit an odour from the pores in their abdomen. They use this defence mechanism when they sense a threat. A major threat to these creatures is to be eaten up by birds or lizards. They release this odour to keep them away.

Apart from that, they certainly cause damage to the houses they choose for overwintering. This is so because, when one stink bug finds a house suitable for overwintering, it releases aggregation pheromone, which attracts thousands of brown marmorated stink bugs to the house. This is the reason why they live in large clusters in one place. This pest infestation is certainly troublesome for the people living in the house as a large population of these pests also attract their predators like lizards in the house.

What you didn’t know about brown marmorated stink bugs is that they are supposed to be in an inactive state during winters, but the warmth of the house makes them active and then they can be seen roaming clumsily about the light fittings. They can be carriers of pathogens and, therefore, can infect food as well. Well, it would hardly make a difference if one or two bugs are roaming about in your house, but remember, that they live in your house in clusters of thousands.

The only solace for the homeowners and tenants is that the female brown marmorated stink bugs are unable to reproduce until early spring, hence, they cannot nest in homes and other buildings. Plus, they do not cause any structural or cosmetic damage to the houses, apartments, office buildings, and condominiums. Usually, homeowners do not even realise that their house is infested because these bugs are mostly inactive and they do not release any smell unless threatened. If your living or office space is infected by brown marmorated stink bugs, you should seek help from professional pest control.

When speaking of do brown marmorated stink bugs bite or cause damage, one cannot ignore the heavy damage to the crops they cause every year in eastern parts of the United States and their native Asian countries.

There you have it! In the above article, we have put in our best efforts to summarise what is brown marmorated stink bug and how it is a big threat to food crops in various parts of the world. The agriculture of the regions infested by these bugs is facing dire threats because their population is growing with every passing year, especially in warmer states. Apart from that, these stink bugs do not bite or sting and, hence, they are no significant threat to humans but they use certain houses and office building to spend winters, which again causes no greater damage apart from attracting their predators to the houses like lizards and other bigger insects.

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