Information About Stink Bugs
Like many insects, the Stink Bug is named for one of its distinguishing qualities or features – when disturbed or crushed, the Stink Bug tends to emit a foul-smelling odor that is hard to eliminate.
Traditionally an agricultural pest, the Stink Bug was accidentally introduced into the eastern United States, specifically into Allentown, Pennsylvania, in the late 90’s. Previously unseen in all of North America, over the last two decades the Stink Bug has become one of the most problematic home invaders across the country – specifically the Brown Marmorated Stink Bug. Unfortunately, they have also become harder to combat now that many species have become resistant to pesticides.
While they may be considered a pest in many parts of the world like the United States, in other countries Stink Bugs are a delicacy. In Mexico, Vietnam and parts of Laos they are a common part of the cuisine - eaten, enjoyed and regarded as delicious, mostly due to their strong odor.
Classifications, Types & Anatomy
The scientific classification of Stink Bugs is (Halyomorpha halys), belonging to the Family Pentatomidae in the Order Hempitera. The term “Pentatomidae” comes from the Greek meaning of five (pente) sections (tomos) as all insects within this Family have antennae that have 5 segments.
The Stink Bug is shield shaped, and like all other insects, has three body segments and six legs. It is a “medium-sized” insect measuring around a ½ inch long.
Aside from their unique antennae, the head segment also contains pierce-sucking mouthparts and a pair of eyes.
Stink Bugs are broad-shaped with triangle-like shields dorsally. They have two pairs of wings attached to their thorax and a pointed spine that protrudes from between the hind two legs. With straight sides and a rounded abdomen, Stink Bugs are usually brown, gray or dark green.
Stink Bugs pass through an egg, larvae and four other nymphal instar stages. The eggs of this species are typically oval shaped, white to pink in color and approximately 1/20 inch long. The top of the egg has a ring of spines and the color of the entire egg will darken as it gets closer to the point of hatching.
The immatures, or “nymphs,” range in size from 2/25 inch in the first instar phase to approximately ½ inch in the fifth and final stage. They all have deep red eyes with a yellow/red abdomen which will progressively change to an off white color as they mature. All of the nymph extremities and the head are black and red in color and all nymphs are wingless.
The most common Stink Bug species that is a pest and home invader in the northeastern United States is the Brown Marmorated Stink Bug.
The Brown Marmorated Stink Bug (BMSB) has certain features that distinguish it from other species in this same family. The adults are typically brown-grey in color, and measure approximately 5/8 inch long. The underside of this species is generally white (sometimes with grey or black markings) while the legs are brown. Both the legs and the antennae have white bands and some abdominal sections protrude from beneath their wings. On the antennae, this is even more pronounced as the different color bands alternate light with dark. The colors of the adult BMSB help to camouflage the insect against the bark of trees; the BMSB nymphs, however, are bright in color, making them more susceptible to predators.
Lifecycle, Breeding & Feeding Habits
Most Stink Bugs, including the Brown Marmorated Stink Bug, are herbivores feeding on plant juices and nectar. They use their mouthparts to pierce fruits or plants and suck the juices out. For some carnivorous species, they use these mouthparts to pierce and drain fluids from caterpillars and other pest insects. In these instances the Stink Bug is a beneficial pest. However, for the most part Stink Bugs in our area, particularly the BMSB feed on fruits and plants such as apples, peaches, soybeans, pears, raspberries, figs, citrus and even cotton during May and June, which can cause fiscal problems for famers along with other agricultural concerns.
Aside from feeding, most of the Stink Bug’s life is spent mating and reproducing. Generally speaking, there is only one generation produced each year (in favorable conditions two or three generations may be produced) although they can produce very large populations given the right environments (however, they will most likely not reproduce during the winter even in their overwintering sites). It only takes approximately 5 days after mating for a female Stink Bug to lay her eggs. Mating season is mainly during springtime and females are able to begin laying eggs after about 27 days from reaching the adult stage. Eggs are generally laid in clusters of 20-30 and are deposited under leaves or other harborage. Eggs within the same cluster will all generally hatch within one hour of each other.
The Stink Bug takes approximately 60 days from hatching to become an adult. After hatching, the Stink Bugs all pass through different nymphal / immature stages. As they progress through these phases the nymphs begin to resemble adults more and more until finally reaching adulthood and getting their wings. A single Stink Bug’s life could span several years.
Environments & Activities
Brown Marmorated Stink Bugs originated in Korea, China and Japan, but more recently have been discovered in the northeastern United States.
Stink Bugs are generally considered to be agricultural pests. They spend most of their lives living near their natural food sources, which mainly consist of plant and fruit juices. They will suck on the juices and destroy crops of apples, figs, citrus and even cotton, along with many others. In these situations they become pests for many farmers and others who rely on agricultural produce for income, rendering vegetation unusable and no longer valuable for sale.
There are some species of Stink Bugs that feed on other insects, such as caterpillars. These predatory Stink Bugs are considered to be beneficial insects that actually help protect crops.
Stink Bugs, specifically the BMSB, will feed on crops and remain close to its food source during the warm weather. Like most insects BMSBs survive the cold by overwintering in houses, causing them to become pests in homes as well. Generally they will travel, as other insects do, by hitchhiking on people and other objects they come in contact with, traditionally through vehicles and commerce. However, Stink Bugs can also fly and therefore expand their range from their home to their food source.
When in homes, Stink Bugs will mostly be found in cracks and crevices, in and around baseboards, windows and door trims. They have also been found in lights or external exhaust fans.
Regardless of its food preference, Stink Bugs are prey for other insect predators and spend their days avoiding being eaten by birds, spiders, assassin bugs and other arthropod predators (including other Stink Bugs).
The peak seasonality for Stink Bug activity is from April when they emerge from their overwintering sites through September when the weather gets colder and indoor harborages become more appealing.
Dangers & Effects on Humans
Stink Bugs don’t bite humans and they aren’t dangerous to people in any other way. They simply affect the lives of people whom they encounter as a result of their daily or natural activities.
BMSBs and all Stink Bugs produce a foul-smelling odor when crushed or disturbed – thus their common name. This odor is the main cause of complaint from homeowners. Additionally, they can become very noisy pests when they start flying around. However, they will rarely reproduce within structures or cause damage to buildings or homes.
While uncommon, Stink Bugs can transmit plant diseases as they feed on certain fruits and vegetables.
Control & Treatment
Stink Bugs have been around for centuries but the Brown Marmorated Stink Bug was only recently introduced into the United States and therefore proper treatment for these insects is still undergoing evaluation.
What has been discovered so far is that BMSBs are resistant to many standard pesticides and the best method for eliminating Stink Bugs is exclusion. Place screens around the doors and windows of a home to provide a barrier for entry. Sealing cracks and crevices with caulk may also provide a line of resistance.
If the nesting source of the Stink Bugs is found they can be removed by hand or vacuum. However, caution is given as disturbing these insects will cause them to emit a foul-smelling odor. This noxious scent may remain in the home or the vacuum cleaner for some time after the insects are removed.
While they are resistant to many chemicals, certain insecticides can also be useful in providing a line of defense against BMSBs. Exterior applications of synthetic pyrethroid may be helpful in certain instances. Always have a local licensed pest control operator, such as Assured Environments, apply any pesticides.