Stink bugs and assassin bugs look similar because both of them are both about 1 inch long. In this article, we discuss the differences between stink bug vs assassin bug in detail.
Stink bugs and assassin bugs look alike, but the similarities end there. Assassin bugs feed on stink bugs and are natural enemies of most other pests in your garden.
Stink bugs are harmless to humans but can be a nuisance pest because they emit a foul odor when you get too close to them.
Assassin bugs are also harmless to humans, but the kissing bug, one type of nocturnal assassin bug, can bite them in the night and cause a deadly disease.
In this article, we explore the differences between these two varieties of insects in terms of their appearance, lifecycle, feeding habits, habitats, and other important differences.
What Do They Look Like?
There are a wide variety of insects in both species, but we have listed some common features in both cases.
Stink bugs have shield-shaped bodies. They have a broader frontal part and a comparatively narrow and rounded posterior. Additionally, they have a triangle-shaped plate on their backs.
Stink bugs have piercing mouthparts which they use to suck sap from plants like aphids and plant-infesting insects.
Most stink bugs have pale green-colored bodies, along with shades of brown coloration.
There are more than 5,000 species of stink bugs, and their physical features can vary from species to species.
For example, the green and the southern green stink bugs look alike, but the green stink bug has a pointed spine between its hind legs which the southern varieties lack.
Assassin bugs have 7,000 subspecies under them. Assassin bugs are often more colorful than stink bugs and can have patterns of colors, including brown, red, yellow, orange, and black.
Their legs are longer than stink bugs, almost similar to crickets. Both the stink bugs and assassin bugs measure about an inch.
However, some assassin bugs, such as the Psyttala horrida, can reach longer sizes of up to 1.8 inches.
Some assassin bugs, such as the kissing bug, are harmful to humans, but no stink bugs are harmful directly to us.
Kissing bugs have either black or brown wings, which might have red, yellow, or orange stripes on their edges.
Do They Bite?
Stink bugs do not bite, but assassin bugs do. However, stink bugs can be harmful in other ways.
Stink bugs are harmless to humans and animals as they neither bite nor are vectors of any disease.
However, some people can develop allergic symptoms such as runny noses, sneezing, and rashes in the presence of brown marmorated stink bugs.
This allergic response is to the odor-causing chemicals that these bugs release as part of their defense mechanism.
Not all assassin bugs bite humans under normal circumstances. However, most of them will bite you if they feel threatened. These are extremely painful bites in most cases.
Assassin bugs release a venomous secretion from their mouthparts to dissolve the tissues of their victims so that they can feed easily on them.
When they bite humans, they release these secretions into your skin, resulting in sharp pain, lesions, and discomfort that might last for weeks.
The kissing bug is the deadliest bug for humans. They bite humans on the face and near the eyes to suck out blood and leave disease-carrying feces behind.
What Is Their Lifecycle?
Stink bugs and assassin bugs undergo a similar life cycle of incomplete metamorphosis. They go from egg to nymph to adult, with several stages of molting in between.
The number of life stages of sting bugs varies from species to species.
The male and female stink bugs are actively involved in mating during the months of autumn and spring. After mating, the female lays eggs.
Later these eggs hatch into nymphs. The female then spends its time feeding these nymphs until they are mature. During this stage, female stink bugs use their piercing mouthparts like beaks to feed their young ones.
The larvae then remain active and continue to grow before the onset of winters, at which time they find places to hide during the harsh weather. They remain dormant for the winter and only come out when the weather is warmer.
Assassin bugs develop from eggs that hatch and give rise to nymphs or undeveloped bugs, which undergo several stages of development to become mature adult bugs.
While the nymphs are wingless, the adults have wings. The nymphs go through five instars (stages of development), and at the last phase of molting, they develop wings.
What Do They Feed On?
One key difference between these bugs is what they eat: stink bugs are pure plant sap suckers, whereas assassin bugs feed on other insects.
Stink bugs can be of many types, and their diet varies for each species. For example, the marmorated stink bugs feed mainly on fruit such as apples, peaches, and other tree fruits.
Most stink bugs feed on plant parts and feast on vegetables, fruits, and raw crops such as soybeans, corn, and beans. They also feed on your ornamental plants.
Stink bugs are considered pests by gardeners.
As the name suggests, assassin bugs are carnivorous and feed on insects such as native stink bugs, sawflies, caterpillars, aphids, and larvae of some beetles.
They also feed on nymphs and adult forms of stink bugs. They are generalist predators and feed on anything that they can find.
Assassin bugs are considered beneficial insects, and many use them in their gardens for pest control.
Where Do They Live?
Stink bugs try to enter homes during winter, but assassin bugs are mostly found outside in the gardens.
During winter, stink bugs find shelter in places such as under a pile of leaves, in your house’s attic, in your dog’s house, chicken coop, or kennel.
They remain in their shelters until the weather warms up when they start moving outside. They are attracted to light and may enter your home if you leave your porch lights on at night.
On the other hand, assassin bugs live close to the nests of the insects they prey on. In short, an infestation of pests in your garden or house may attract assassin bugs.
Like we said earlier, some assassin bugs can be harmful. Beware of kissing bugs that spread diseases and bite humans. Kissing bugs are mostly found in southern regions of the United States.
Do They Cause Diseases?
As mentioned earlier, stink bugs do not usually bite humans and so do not cause any direct skin disease or inflammation.
But, you should note that they can transmit diseases indirectly. Most stink bugs eat fruits leaving behind a “cat-faced” deformity. Eating this damaged fruit can be harmful.
Stink bug infestation can dramatically reduce the growth of soybean and other plants because they suck the nourishing sap from the plants.
Assassin bugs can cause disease, especially kissing bugs that bite on the face. These bugs are known to transmit a disease called Chagas Disease.
Kissing bugs are hematophagous insects, which simply means they feed on your blood. They do so by piercing a few layers of your skin and inserting their mouthparts into a blood capillary.
If you rub the area after an assassin bug stinks, the feces get inside and into the blood. If you somehow get the feces into your eyes, you can get an eye infection as well.
If you see this bug in your home, you should immediately think about pest control. Chagas Disease kills over 10,000 people every year.
Frequently Asked Questions
Are assassin bugs and stink bugs the same thing?
No, they are not the same at all. Assassin bugs are predators of stink bugs. They also have different features, colors, and feeding habits.
Although their nymphal stages are indistinguishable, adult assassin bugs have more colorful bodies with various patterns.
Do assassin bugs eat stink bugs?
Yes, assassin bugs eat stink bugs. They also eat many other insects like aphids, sawflies, and caterpillars. They are a type of biological control for these pests.
But you need to be careful while bringing assassin bugs into your house for pest control. Some types of assassin bugs suck human blood and cause diseases.
Are assassin bugs harmful to humans?
Most assassin bugs are harmless to humans, but some species of assassin bugs, such as kissing bugs, can be dangerous.
They are known to bite your face (near your lips and eyes, which is why the name). Although their bite is not very painful, it can carry Chagas disease, a potentially fatal disease.
What happens if a stink bug bites you?
Stink bugs do not generally bite humans or our pets. They enter human homes when the outside temperature drops.
Stink bugs can cause allergic reactions in some people, especially those who already have allergies to cockroaches and other insects.
Assassin bugs and stink bugs look very similar at the nymphal stage of their lives. But as they become mature, you can easily tell the difference between the two.
Although assassin bugs can control a stink bug infestation, it is not wise to release assassin bugs into your home as some of these bugs are harmful.
Thank you for reading!
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Sycamore Assassin Bug
Subject: Orange Insect with Itty Bitty Head Location: Northern Burbs of Atlanta April 18, 2013 11:43 am My daughter spotted this bright interloper on our bookshelf this afternoon. We’ve never seen an insect like this before and were at a loss for its identity. If pushed I’d say it was a type of assassin bug since it bears physical characteristics like its itty bitty head to others I’ve seen. Is it an assassin bug? And if so is it one with a painful bite? After the photo shoot I gently relocated it outdoors. Thanks for your assistance. P.S. Sorry for the poor detail quality of the pics. I only had my camera phone handy. Signature: Resa Dear Resa, We actually love your photo. This is a Sycamore Assassin Bug in the genus Pselliopus and if memory serves us correctly, it is one of the species that will more readily bite. The bite of an Assassin Bug can be quite painful, though it is not considered dangerous. As with many things, reactions can vary between individuals. You should caution the children not to handle the Assassin Bugs. The Prince William Conservation Alliance has a beautiful image of a Sycamore Assassin Bug.
Letter 2 – Sycamore Assassin Bug Metamorphosis
Subject: Did he eat his sibling? Location: Andover, NJ – backyard July 9, 2013 2:28 pm I found an assassin bug nymph in my garden today and happily set about photographing it when I noticed what I first thought was a second nymph. But, as I watched, the white ”nymph” wasn’t moving and on closer look appeared to be just an empty shell/skin. So, did the orange nymph shed its skin or did it possibly kill a sibling? Signature: Deborah Bifulco Dear Deborah, This is not sibling cannibalism. Rather is is the metamorphosis of a Sycamore Assassin Bug from one instar to a later instar. The shed skin is known as the exuvia.
Letter 3 – Sycamore Assassin Bug
Subject: What is this bug? Location: SE Oklahoma November 18, 2013 10:31 am Iv only ever seen this type of bug once before. After much web surfing, I still cant identify it. What is it? Signature: Just wondering Wonder no more. This is a Sycamore Assassin Bug. Though they are not considered aggressive toward humans, they can inflict a painful bite. We just approved a comment to a previous posting that details the effects of the bite of a Sycamore Assassin Bug on one individual, though we suspect the effects of the bite will vary from person to person.
Letter 4 – Orange Spotted Assassin Bug
Subject: Odd bug. Location: US July 13, 2014 2:44 pm My mom was about to wash dishes when she all of a sudden got a sharp pain in her finger. She said it felt like being cut by glass. It blistered immediately. We’ve never really seen this bug before. If you could identify this bug, that’d be great. Thank you so much in advance. Signature: -Stevie Jaramillo Hi Stevie, This Orange Spotted Assassin Bug or Corsair in the genus Rasahus is not considered dangerous, however we frequently receive reports from people who have been bitten and we understand the bite is quite painful. Thanks for the reply. We had no idea what that bug was, so I had saved it in a ziploc just in case my mom had any reaction to the bite. But thank you for the reply and peace of mind.
Letter 5 – Thread-Legged Assassin Bug
Subject: found at a Mass Audubon Sanctuary Location: Natick, MA August 8, 2014 9:19 am Wondering what this is. My son sent me the photo, so I don’t know if those are mandibles or legs or something else. And I don’t know how many pairs of wings it had. Looks like a mantis or mantid fly or something like that. Thanks. Signature: glen Dear Glen, This appears to be a Thread-Legged Assassin Bug in the subfamily Emesinae, and the species it most closely resembles on BugGuide is Stenolemoides arizonensis, a species reported from Arizona and Utah. We suspect your individual is a different species that is perhaps closely related. Those raptorial front legs are found in numerous species of unrelated insects that capture prey, including Mantids, Mantispids and Water Scorpions as well as the Thread-Legged Bugs.
Letter 6 – Milkweed Assassin Bug
Subject: Help please. Location: Miami, Florida August 11, 2015 9:27 am I have a lot of these bugs on my Lemon tree, and I was wondering what they were? I took these pictures myself. I appreciate a response from you. Thank you for the hard work you do. Signature: No signature required You have no cause for concern as your lemon tree is in good hands. This is a predatory Milkweed Assassin Bug, Zelus longipes, and it will help keep your lemon tree free of agricultural pests. Though your individual does not have the typical black markings associated with the Milkweed Assassin Bug, we found a matching image on BugGuide, also from Florida, that may indicate individuals from Florida are more orange than black.
Letter 7 – Spined Assassin Bug from Canada
Subject: Pink Assessin/long nosed bug Location: Courtice , ontario December 1, 2015 5:35 pm Hello It has been awhile since I asked for an ID . I am going over my summer pics of insects and I have a couple I would love identified . Location Courtice, Ontario. In a field near courtice arena. One is a pink prickly looking bug the other a long nosed bug. Signature: Terri Martin Dear Terri, Your Assassin Bug is a Spined Assassin Bug, Sinea diadema, and you can compare your image to this image on BugGuide.
Letter 8 – Milkweed Assassin Bugs
Subject: Bug on Japanese Blueberry tree Location: LOUISIANA January 24, 2016 5:23 pm What is this bug on my Japanese Blueberry tree? The tree also has the sooty mold. What should I do about this? Signature: Denise Arsenaux Dear Denise, These are Milkweed Assassin Bugs, Zelus longipes, both winged adults and wingless nymphs, and they are a beneficial predatory species that will help keep your tree free of insect pests. Your image, which we have cropped closer into several different views, documents an aggregation which is quite unusual. Generally, especially when they are adults, Assassin Bugs are solitary hunters. They must have found something to feed upon on your tree, perhaps Aphids or some other plant feeding pest. That pest may be contributing to the sooty mold problem. You can compare your Milkweed Assassin Bugs to those depicted in the images posted to BugGuide.
Letter 9 – Pale Green Assassin Bug
Subject: Insect ID Location: Northampton, MA, USA May 29, 2016 11:39 am I was using a new macro lens the other day and found this insect. Try as I might – and I am quite skilled in Internet searches- I was unable to identify it. I even posted it on my FB page and friends have suggested beetle, lacewing, male praying mantis or katydid. I just don’t see it. If, when you identify, you could also explain the 2 black tips, I would appreciate it. Thanks very much! Signature: Keitheley Wilkinson Dear Keitheley, Thanks to this BugGuide image, we are confident that your Assassin Bug is Zelus luridus, a species commonly called the Pale Green Assassin Bug, which BugGuide notes is “rather unfortunate invention, given color variation.” BugGuide also notes: “The base color of Z. luridus is apple green, and markings on the back may be very dark or rather light. The legs sometimes have dark or red bands on the distal ends of the femurs, but these can often be so light as to be almost invisible. When I’ve seen mating pairs, the males tend to be the darker ones, with the more pronounced red leg bands. The best feature for recognition is the pair of delicate spines on the rear corners of the pronotum, which are rather long on the light colored individuals and shorter on the dark.” The “2 black tips” to which you refer are those delicate spines, and we suspect they may have evolved to make swallowing a Pale Green Assassin Bug more difficult, thereby dissuading predators.
Letter 10 – Milkweed Assassin Bug
Subject: What is this bug Location: LA-lower AL June 24, 2016 7:07 am What is this bug on my plants. Signature: Helen Dear Helen, This is a beneficial, predatory Milkweed Assassin Bug, and it will help keep your plants free of phytophagous species. We would urge you not to try to handle Milkweed Assassin Bugs as they are prone to biting if they feel threatened, though the bite is not dangerous and will produce little more than local swelling and irritation.
Letter 11 – Immature Spiny Assassin Bug
Subject: small insect with long front legs Location: Greenville, SC June 26, 2016 7:37 pm Hello bugman! I saw this bug on my thai hot pepper plant today. It’s been quite hot outside lately. He was pretty still and he was the only one of his kind that I saw. I thought he was a pseudoscorpion at first, but I couldn’t find any that have the same markings, and I’m pretty sure he has antennae, as well. Signature: ronnet sonnet Dear ronnet sonnet, This is a predatory, beneficial, Spiny Assassin Bug nymph in the genus Sinea. You can compare your image to this image on BugGuide.
Letter 12 – Pale Green Assassin Bug
Subject: What’s that bug? Location: Columbia, SC July 8, 2016 8:59 am I found this (see picture) on my front door frame, near my potted herbs. Can you help me identify it? Perhaps give me the latin name so i can read up about it. Signature: OJ Dear OJ, We believe we have correctly identified your beneficial, predatory Pale Green Assassin Bug as Zelus luridus thanks to this BugGuide image.