Bed bugs finding them


7 Early Signs to Look For

Worried about having bed bugs in your home? In this article, we’ll explain the 7 early signs of bed bugs that you should look out for:

  • Live bed bugs
  • Bed bug eggs
  • Shell casings
  • Fecal marks
  • Bloodstains on sheets
  • Bed bug bites
  • Musty odors

Bed bugs are notoriously hard to find and even harder to get rid of, especially if you live in densely populated places like New York City.

But despite their sneakiness, it isn’t impossible for a vigilant homeowner or apartment renter to recognize the early signs of a bed bug infestation.

One of the best ways to protect yourself and your family from these tiny, blood-sucking pests is to find and exterminate them early on — before they can reproduce and spread.

This article will explain the 7 early signs of bed bugs, as well as where bed bugs hide and how to perform a simple visual inspection of your home.

7 Early Signs of Bed Bugs

These signs of bed bugs are ranked in order of how much certainty each warning sign can provide when it comes to confirming the presence of bed bugs, especially at the beginning of an infestation.

We’ll start with the least reliable sign (odors) and work our way to the most reliable sign (live bed bugs), explaining what each one means and where to look.

Bed Bug Odors

Bed Bug Bites

Bloodstains on Sheets

Fecal Marks / Spotting

Shell Casings / Shed Skins

Bed Bug Eggs

Live Bed Bugs

If you suspect that bed bugs have invaded your home, it’s well worth your time to understand and familiarize yourself with these early warning signs.

In general, these signs of bed bugs may require professional confirmation to be certain of bed bugs, but this article will give you an idea of when to seek out that professional confirmation.

#7: Odors
  • An unusual, musty odor with no apparent cause
  • Bed bug pheromones are often compared to the scent of raspberries, coriander, cilantro, or almonds
  • A severe bed bug infestation may smell like rust, wet towels, and moldy laundry

Sometimes, the first hint that something is amiss comes from our sense of smell. If you notice an unusual, musty odor in your bedroom that doesn’t seem to originate from an obvious source — like a pile of dirty laundry — it might be an early sign of bed bugs.

Bed bugs emit “alarm” pheromones in response to being bothered or threatened. These pheromones produce certain odors that may smell slightly sweet or musty. People who have experienced it firsthand describe the smell as somewhat similar to raspberries, coriander, cilantro, or almonds.

Normally, the smell of pheromones is very faint — practically imperceptible to the human nose. Unless you’re a trained bed bug-detecting canine, your chances of noticing the raspberry-like pheromone smell from bed bugs are very low.

When you have a large number of bed bugs living together, the smell of their pheromones gets mixed together with the odor of dead bed bugs, shed shell casings, and bed bug excrement. The result is an unpleasant, rusty smell that gets worse as the infestation grows more severe.

Compared to other early signs of bed bugs, odor is typically the least reliable. That’s simply because when there are only a few bed bugs around, their odor is too faint for humans to notice. Furthermore, most people aren’t familiar with the scent of bed bugs — or a bed bug infestation — so even if you sense something, you’re likely to mistake the smell for something else.

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#6: Bites
  • Small, red, itchy bumps that mysteriously appear at night
  • The most common places for bites are the arms, hands, and legs
  • Sometimes appears as clusters of 3 or 4 bites in a line (the so-called “breakfast, lunch, and dinner” pattern)

Many people consider waking up to find mysterious insect bites as the first sign of bed bugs.

Bed bugs are considered nocturnal insects that prefer to feed on our blood while we sleep. Therefore, their bites typically appear on skin that is exposed during the night. The most common places where people get bitten are the arms, hands, and legs.

However, pest control professionals agree that bites alone are not enough to diagnose a bed bug problem. That’s because different people can react very differently to bed bug bites, so there’s no definitive way to distinguish them from other insect bites. In fact, a whopping 30% of people don’t exhibit any skin reactions at all to bed bug bites.

While everyone reacts differently, the most common symptom of bed bug bites is red, itchy bumps appearing in small clusters. Some people refer to this as the “breakfast, lunch, and dinner” pattern, which describes bed bug bites as appearing in small clusters or lines of 3 bites. But in reality, bed bug bites can also appear as single bites or in random patterns.

As a side note, bed bug bites are usually not dangerous and do not transmit any known diseases. However, some people may experience allergic reactions to certain chemicals in bed bugs’ saliva. If you’re experiencing severe itchiness, painful swelling, blisters, fever, or flu-like symptoms after being bitten, you should seek professional medical attention.

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#5: Bloodstains
  • Unexplained red or rust-colored bloodstains
  • May appear as small splotches or smears on bedsheets, clothing, or pillows
  • Double check first for other probable causes

Even though we don’t notice bed bugs when they’re feeding on us, they don’t always get away unscathed.

After a bed bug becomes engorged with blood, its original flat, seed-like appearance changes into a round, bloated form resembling a tiny football. If you suddenly move or shift your body in your sleep, you might inadvertently crush or squeeze a bed bug that just finished feeding.

While it doesn’t usually kill them, it can cause some of the blood they just fed on to leak out and create a noticeable red or rust-colored stain.

If you see something that appears to be a bloodstain on your sheets, clothes, or pillow, check your body first to see if you can find a cut or scab that might be the cause. If there’s no other explanation for the bloodstain, then it might have been left behind by an unlucky bed bug.

Sometimes, bloodstains might also come directly from bed bug bites. Bed bug saliva contains an anticoagulant that prevents blood from clotting while they feed. After they finish their meal, the bitten areas may continue to bleed for a short while.

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#4: Fecal Marks
  • Tiny, dark brown or black spots around the size of a pen tip
  • Usually clustered around harborage areas, but can also be found on sheets and clothing.
  • Dark smears on fabric resembling magic marker stains after being washed

Compared to the bloodstains that we described above, bed bug fecal marks (also called “fecal spotting”) are much smaller and darker.

These small, dark spots resemble an ink dot from the tip of a pen or marker. Their average size is about 2 to 4 times larger than a period at the end of this sentence.

Fecal marks come from bed bug droppings, which consist of digested human blood. The digested blood appears dark brown or black in color and, because it contains iron, will give off a faint, rusty smell that contributes to the overall unpleasant odor of a bed bug infestation.

Bed bug fecal spotting can occur anywhere — on sheets, pajamas, mattresses, headboards, box springs, walls, curtains, and other types of surfaces. You can usually find them in large numbers around bed bug hiding places and harborage areas.

On fabric, bed bug fecal marks can be quite difficult to wash out. Water causes them to smear in a distinctive fashion, resembling magic marker stains.  

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#3: Eggs
  • Pinhead-sized, pearly white ovals around 1 mm in length
  • Loosely stuck to various types of surfaces
  • Usually found near bed bug harborage areas

Pregnant female bed bugs lay between 1-7 eggs per day, which typically hatch in the next 7-10 days.

In terms of appearance, bed bug eggs are about 1 millimeter long, pearly white in color, and ovular in shape. They resemble tiny grains of rice that are miniaturized to the size of a pinhead.

Eggs are visible to the naked eye, but they can be difficult to recognize unless you know what you’re looking for. At the end of each egg is a hinged cap, which is where the newly hatched beg bug emerges from. Bed bug eggs that are more than 5 days old have a darkened eye spot — however, this can only be seen under a microscope.

Here are some pictures of what bed bug eggs look like.

Hatched bed bug eggs on the fabric of a box spring. (Source: Gary Alpert, Harvard University, Bugwood.org)Bed bug eggs in a crevice between cushions. (Source: Ben Hottel, University of Illinois)
Bed bug eggs in upholstered furniture. (Source: Ohio State University)

Similar to fecal spotting, bed bug eggs are also more common around harborage areas. However, female bed bugs tend to wander around when they’re pregnant, potentially spreading the infestation to other areas as well as neighboring apartments.

When depositing their eggs, they use a glue-like material to adhere them to surfaces. As a result, you’ll most likely find these tiny, white eggs loosely stuck to crevices between fabrics or wooden surfaces — although they could really be anywhere.

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#2: Shell Casings
  • Yellowish-brown, translucent exoskeletons of juvenile bed bugs
  • Comes in various sizes throughout the bed bug’s molting cycle
  • Reliable indicators of a bed bug infestation

If you find bed bug shell casings, also known as husks or shed skins, there’s a very high probability that you have bed bugs. Abandoned shell casings are a reliable early sign of a growing bed bug infestation.

Shell casings are translucent, hollow outlines of juvenile bed bugs, and they’re often easier to find than the bed bugs themselves. They can be found anywhere that bed bugs hatch and breed — check mattress seams, upholstered furniture, and in holes, cracks, and crevices within wooden furniture.

As bed bugs go through 5 lifecycle stages before reaching adulthood, they’ll shed their exoskeleton several times. Molting is done at each step of the lifecycle, from the 1st instar nymph to the 2nd instar to the 3rd instar to the 4th instar to the 5th instar and finally to the final adult form.

The result of this process is what we call “shell casings” or “shed skins” in various sizes. This makes identifying shell casings a bit tricky because most people aren’t familiar with the sizes and shapes of bed bug nymphs.

However, if you already suspect bed bugs and you discover yellowish, translucent shells in common bed bug hiding places, then you should consider contacting your local pest control professional for an inspection.

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#1: Live Bed Bugs
  • Small, reddish-brown insects around the size of flaxseeds
  • Prefers to hide in tight cracks and crevices
  • Often confused with spider beetles, carpet beetles, and other small insects

Finally, the most obvious sign: live bed bugs.

Normally, bed bugs don’t like to wander around unless they need to feed or unless they’re pregnant females avoiding overzealous males. Bed bugs typically tend to find a hiding place and stick to it.

For this reason, many people never see live bed bugs until the infestation becomes severe. Only when their hiding places are disturbed, like when you’re packing for a move, will live bed bugs be easily discovered.

You’d think finding a live bed bug in your home would be a smoking gun, but it’s not always that simple.

Many insects are often confused with bed bugs and vice versa. In our experience, the most common insects that people mistake for bed bugs are spider beetles, carpet beetles, and cockroach nymphs.

Another common misconception is that people think of bed bugs as being the size of apple seeds. This isn’t exactly true — bed bugs are actually quite a bit smaller than apple seeds.

An average apple seed is about 8 mm in length, while adult bed bugs are usually only 4-5 mm long (although after becoming engorged with blood, they can temporarily reach up to 7 mm). Bed bug nymphs are even smaller, starting at around 1 mm in length.

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Where Do Bed Bugs Hide?

With their tiny, flat bodies, bed bugs can squeeze themselves into just about any crack or crevice that’s bigger than 2 millimeters.

They tend to hide in the seams of mattresses, in the joints of furniture, inside cracks and crevices within walls and baseboards, and even inside electrical outlets or along the folds of curtains. These are all areas that you’ll want to thoroughly check for the early signs of bed bugs mentioned above.

From our experience as professional bed bug exterminators in NYC, here are some very common examples of bed bug harborage areas:

  • Your Bed — pillows, bedsheets, mattress seams, headboards, bed frames, and box springs
  • Next to the Bed — nightstands, dressers, rugs, and storage boxes
  • Furniture — couches and cushions, bookshelves, tables, desks, chairs, rugs, and pet beds
  • Walls — wallpaper, baseboards, window and door frames, curtains, pictures and posters, electrical outlets, and smoke alarms
Pillow casesBed framesMattress seams

How to Perform a Visual Inspection for Bed Bugs

To perform a simple visual inspection for bed bugs at home, you’ll need a flashlight and a thin card (could be an extra business card, playing cards, or an old credit card).

  1. Examine pillows and bed sheets for fecal marks and bloodstains.
  2. Remove bed sheets and check around the edges and seams of your mattress for bed bugs, shell casings, and eggs.
  3. Remove the mattress and use your flashlight to search the crevices, corners, nooks, and crannies around your bedframe and headboard.
  4. For any cracks that are too small to see into, slide your card inside and use the thin, rigid edge to extract any bed bugs or debris hidden inside.
  5. Do the same thing to inspect nearby dressers, nightstands, and other wooden furniture. Pay attention to screw holes, which is another common hiding spot for bed bugs.
  6. Pull furniture away from the walls to check the backs and baseboards.
  7. Inspect couches and upholstered furniture by removing cushion covers and using your card to get into gaps and crevices.

Tips for Identifying Bed Bugs

We wrote a whole article about what bed bugs look like. Here are some additional tips for recognizing and identifying adult bed bugs:

  • Bed bugs have a narrow head and thorax with a flat, oval-shaped abdomen.
  • They have 2 beady, black eyes that protrude out from the sides of their heads.
  • They have 6 legs and 2 antennae. Their antennae have 4 segments and stick out from the front of their heads.
  • Bed bugs have small, vestigial wing pads but they can’t fly. If it flies, it’s definitely not a bed bug.
  • Adults are flat and brown/rusty colored, while nymphs are pale. Once fed, they elongate slightly and turn reddish.
  • Bed bug interceptors (also called monitors or indicators) are a great tool to help catch and identify bed bugs.

Still Not Sure if You Have Bed Bugs?

MMPC offers a free Pest Identification Service, so you can simply send a picture of any of the above signs and we will get back to you within a business day to help you confirm if you may have bed bugs. We are also happy to answer any of your questions (free of charge) and provide recommendations for next steps.

Bed bugs are a heavy burden to bear, and getting rid of them is a team effort. Hopefully, you now have a better idea of when to call in that team.

For more articles and information about bed bugs, please see our resource page and pest blog.

Contact Us — MMPC

Bed Bug Resources:
  • How to Check for Bed Bugs: Performing a Self-Inspection of Your Home or Apartment
  • What Do Bed Bugs Look Like & How to Identify Them
  • What Do Bed Bug Eggs Look Like? (Pictures)
  • Where Do Bed Bugs Hide? — An Entomologist Explains
  • 5 Ways to Find Bed Bugs during the Day
  • NYC.gov – “Preventing and Getting Rid of Bed Bugs Safely”
  • Scientific American – “Bed Bug Confidential”
  • Medical News Today – “Bed Bug Bites”

How to Identify Bedbugs and How to Get Rid of Them

Written by Mary Anne Dunkin

In this Article

  • Where Bed Bugs Hide
  • When Bedbugs Bite
  • Signs of Infestation
  • Bedbug Treatments
  • Bedbug Extermination

Bedbugs are small, oval, brownish insects that live on the blood of animals or humans. Adult bedbugs have flat bodies about the size of an apple seed. After feeding, however, their bodies swell and are a reddish color.

 

Bedbugs do not fly, but they can move quickly over floors, walls, and ceilings. Female bedbugs may lay hundreds of eggs, each of which is about the size of a speck of dust, over a lifetime.

Immature bedbugs, called nymphs, shed their skins five times before reaching maturity and require a meal of blood before each shedding. Under favorable conditions the bugs can develop fully in as little as a month and produce three or more generations per year.

Although they are a nuisance, they are not thought to transmit diseases.

Where Bed Bugs Hide

Bedbugs may enter your home undetected through luggage, clothing, used beds and couches, and other items. Their flattened bodies make it possible for them to fit into tiny spaces, about the width of a credit card. Bedbugs do not have nests like ants or bees, but tend to live in groups in hiding places. Their initial hiding places are typically in mattresses, box springs, bed frames, and headboards where they have easy access to people to bite in the night.

Over time, however, they may scatter through the bedroom, moving into any crevice or protected location. They may also spread to nearby rooms or apartments.

Because bedbugs live solely on blood, having them in your home is not a sign of dirtiness. You are as likely to find them in immaculate homes and hotel rooms as in filthy ones.

When Bedbugs Bite

Bedbugs are active mainly at night and usually bite people while they are sleeping. They feed by piercing the skin and withdrawing blood through an elongated beak. The bugs feed from three to 10 minutes to become engorged and then crawl away unnoticed.

Most bedbug bites are painless at first, but later turn into itchy welts. Unlike flea bites that are mainly around the ankles, bedbug bites are on any area of skin exposed while sleeping. Also, the bites do not have a red spot in the center like flea bites do.

People who don't realize they have a bedbug infestation may attribute the itching and welts to other causes, such as mosquitoes. To confirm bedbug bites, you must find and identify the bugs themselves.

Signs of Infestation

If you wake up with itchy areas you didn't have when you went to sleep, you may have bedbugs, particularly if you got a used bed or other used furniture around the time the bites started. Other signs that you have bedbugs include:

  • Blood stains on your sheets or pillowcases
  • Dark or rusty spots of bedbug excrement on sheets and mattresses, bed clothes, and walls
  • Bedbug fecal spots, egg shells, or shed skins in areas where bedbugs hide
  • An offensive, musty odor from the bugs' scent glands

If you suspect an infestation, remove all bedding and check it carefully for signs of the bugs or their excrement. Remove the dust cover over the bottom of the box springs and examine the seams in the wood framing. Peel back the fabric where it is stapled to the wood frame.

Also, check the area around the bed, including inside books, telephones or radios, the edge of the carpet, and even in electrical outlets. Check your closet, because bedbugs can attach to clothing. If you are uncertain about signs of bedbugs, call an exterminator, who will know what to look for.

If you find signs of infestation, begin steps to get rid of the bugs and prevent their return.

Bedbug Treatments

Getting rid of bedbugs begins with cleaning up the places where bedbugs live. This should include the following:

  • Clean bedding, linens, curtains, and clothing in hot water and dry them on the highest dryer setting. Place stuffed animals, shoes, and other items that can't be washed in the dryer and run on high for 30 minutes.
  • Use a stiff brush to scrub mattress seams to remove bedbugs and their eggs before vacuuming.
  • Vacuum your bed and surrounding area frequently. After vacuuming, immediately place the vacuum cleaner bag in a plastic bag and place in garbage can outdoors.
  • Encase mattress and box springs with a tightly woven, zippered cover to keep bedbugs from entering or escaping. Bedbugs may live up to a year without feeding, so keep the cover on your mattress for at least a year to make sure all bugs in the mattress are dead.
  • Repair cracks in plaster and glue down peeling wallpaper to get rid of places bedbugs can hide.
  • Get rid of clutter around the bed.

If your mattress is infested, you may want to get rid of it and get a new one, but take care to rid the rest of your home of bedbugs or they will infest your new mattress.

Bedbug Extermination

While cleaning up infested areas will be helpful in controlling bedbugs, getting rid of them usually requires chemical treatments. Because treating your bed and bedroom with insecticides can be harmful, it is important to use products that can be used safely in bedrooms. Do not treat mattresses and bedding unless the label specifically says you can use them on bedding.

Generally it is safest and most effective to hire an experienced pest control professional for bedbug extermination.

Skin Problems & Treatments Guide

  1. Skin Discolorations
  2. Chronic Skin Conditions
  3. Acute Skin Problems
  4. Skin Infections

How bed bugs find humans - 5 "search receptors"

We tend to think that the spread of ectoparasites, such as lice or fleas, is associated with poor sanitation, and that this is a problem in developing countries or disadvantaged areas. Bed bugs have come as a big surprise by infesting prosperous metropolitan areas in the last 20 years: New York, Paris, London and many others. Bed bug experts sound the alarm

  1. How bed bugs find you when you're in another room
  2. How bugs find a person by breathing
  • CO2 mobilizes and guides bedbugs
  • No CO2 - no search
  • "Combing" tactics
  • Can bedbugs feel the warmth of the human body
  • Can bedbugs find a person by smell
  • How do bedbugs use their eyesight
    • Perception of colors
    • Response to vertical objects
    • In what light can bed bugs see
  • How bedbugs navigate by surface texture
  • Complex search engine
  • In search of reasons, biologists began to study the behavior of these insects, and first of all the question of how bedbugs find a person.

    Despite our squeamish disgust, bed bugs have been faithful companions of people for centuries. They cannot live without us. After all, human blood is the only food acceptable for bedbugs, without it they do not breed, do not grow and die. Not surprisingly, in the natural navigator of these insects, one of the main “default settings” is the search for a person.

    Looking for new sources of food, unwanted lodgers even master new cities and countries, to say nothing of the next room.



    How bed bugs find you if you are in another room

    Insects receive information about the outside world in a completely different way from mammals. They have poorly developed vision and hearing, but other senses allow them to perfectly navigate the terrain by the chemical composition of the air, temperature, brightness of light, smell and surface texture. By scanning these environmental parameters, arthropods decipher them as Morse code, and obtain the necessary data.

    How bed bugs find their prey is also based on chemical and biological signals, and some of them we send ourselves without even knowing it.

    It would be very naive to believe that if you move to sleep in another room, the bugs will be confused and die of grief. They have a “map and compass” in their arsenal, according to which they will make an accurate route to your new sleeping place and set up their next camp there. Read about these biological “devices” and how bed bugs use them to find the human body and the way home in this article.

    How bed bugs find a person by breathing

    According to science, the carbon dioxide (CO2) that we emit when we breathe is the most powerful attractant for bed bugs. Scientists came to this conclusion at the beginning of the last century, and numerous studies have confirmed this.

    Attractants are substances that attract living organisms and influence their behavior.

    For example, in 2009 a team of scientists at the Agricultural Experiment Station in New Haven, Connecticut, tested laboratory bed bug traps in infested city apartments using multiple attractants in various combinations. They used carbon dioxide, heat and 5 different chemical baits (propionic acid, butyric acid, valeric acid, octenol and lactic acid).

    The result speaks for itself: in 29 days, 656 bedbugs were caught in traps with different combinations of heat and chemicals (without CO2); and CO2 traps collected 5898 individuals in 9 days.

    An impressive difference, isn't it!


    For information on bed bug traps you can use in your home, see: Bed bug traps

    CO2 mobilizes and directs bed bugs

    Another study on how bed bugs find humans was done in 2010 by James T. Sachi and Vernard R. Lewis from the University of California. In their experiments, the scientists compared the behavior of hungry bed bugs in the presence and absence of human breath.

    The experiment looked like this:

    In the center of a square area (91.44 × 91.44 cm) there was a folded sheet of special paper imitating a shelter with five bugs of the same floor. A tube led out to one corner of the site, connected by a hose to the next room. A person participating in the experiment breathed through this hose behind the wall. The site was illuminated by a lamp with a red light filter, and a digital camera was fixed on top to photograph the activity of insects.

    Under such conditions, it is possible to analyze how bedbugs find a person at night by breathing. Red light made it possible to do without a camera flash.

    The experiment was repeated 4 times (with and without human respiration) for adult bugs of each sex. One repetition lasted 10 minutes, while the camera connected to the computer continuously filmed, taking a frame every 5 seconds. Based on the results of the experiment, scientists analyzed many parameters of bedbug activity: distance traveled, average speed, number of stops, tortuosity and purposefulness of movement relative to the breathing tube, etc.

    An example of their trajectory can be seen on the graph.

    The breathing tube is marked with a thick black dot, and the artificial shelter of bedbugs is marked with a white cross in the center (the numerical values ​​of the axes are indicated in centimeters). In picture (a) on the left, the subject is breathing into a tube, but in picture (b) he is not.

    We note a couple of results from this study.

    No CO2 - no search

    When carbon dioxide was not supplied, 86% of males and 82% of females never left their shelter. When human breath appeared, only 19 remained in the shelter.% males and 13% females.

    This observation suggests that the bugs are able to rationally spend their energy. After all, the search for food for them is a double-edged sword. On the one hand, they need blood, on the other hand, an active search for a victim where there is none is a waste of energy. At the same time, these parasites in a passive state are able to do without food for more than a year.

    If you decide to move out of an infested apartment for a while to starve the bed bugs, they have a plan "B" for this case.

    And one more thing. After treating the premises with contact-type insecticides, which are usually used by disinfection services, it is important that all bedbugs crawl out of their shelters in the next 10-15 days. Otherwise, the processing will be inefficient.

    How can they be lured out of there? That's right - the method "on live bait"! If during this control period no one will spend the night at home, the bugs can safely sit out in their crevices. After that, poisoning them will be even more difficult.


    What else are bedbugs afraid of, besides pesticides, read the article: What are bedbugs afraid of

    "Sweeping the area" tactics

    Watching how bedbugs find a person by breathing, scientists have noticed that these insects rarely move towards the target in a straight line. Their route is usually winding.

    Strategically spiraling increases the chances of a successful search. Such a reaction to the presence of a person characterizes bedbugs as active parasites. If the bug is hungry, then he will rather go in search of the nearest victim than wait until she approaches him herself. Thanks to this tactic, bloodsuckers move into neighboring rooms and even apartments.

    But carbon dioxide as a product of respiration is not the only guide by which bed bugs find a person.

    Do bedbugs feel the heat of the human body?

    Bed bugs live in close proximity to humans and regularly seek physical contact with them.

    With such a way of life, the ability to capture the thermal radiation of the body would be extremely useful to them. Indeed, in how bedbugs find a person, their sensitivity to temperatures plays an important role.

    Entomologist Zachary Devries and his colleagues at the University of North Carolina have been working on this issue. Scientists studied the effect of a heat source on the activity, directional movement and feeding of bed bugs. What did they manage to find out?

    Heat baits with a heating element were used to attract bed bugs. At the same time, the temperature spectrum from +22˚С to +48˚С was considered.

    Whenever during the experiment the temperature of the heating element rose above the ambient temperature, the insects became active and began to move to where it was warmer. The higher the temperature of the source, the faster the bug approached it. Even when the heating element became 2-3 degrees warmer than the air, the reaction of the bugs accelerated sharply.

    This shows that bedbugs are very sensitive to the slightest temperature difference. That's just the distance at which the heat source causes a response in them, does not exceed 3 centimeters.

    Therefore, the thermal "sensor" carries the function of a short-range search, which the bugs connect at the right time as they approach the target.

    Can bedbugs find a person by smell

    Volatile substances and their smells are an important element of the chemical language of insects. Through it, they receive the necessary information about the outside world and communicate with each other.

    Biologist Vincent Harraka and his research team studied the role that the ability to identify odors plays in how bed bugs find humans.

    First, they found out how the sensilla on the antennae of the bugs react to various volatile substances. A pronounced reaction of sensilla meant that this smell would somehow influence the behavior of the insect. So scientists found that 5 substances caused a significant reaction of sensilla: 4 aldehydes and 1 ketone.

    They then studied how the presence of each of these odors in the biological environment of the insects affected their behavior. It turned out that concentrated odors of aldehydes repelled bedbugs, while those diluted by 10 and 100 times attracted, but very weakly.

    It turned out that, in general, bedbugs react to human odors much less than other insects, such as mosquitoes or tsetse flies. The authors believe that the susceptibility to our body odors in different parasites depends on the degree of proximity of their range to humans. Mosquitoes and tsetse flies have to search for their prey at a great distance, so they need to have a good “smell”. And the bugs live closer, and the sense of smell is not so important for them.

    It is known that bedbugs not only catch odors, but also emit them themselves. Using smells as a means of communication, bedbugs find and, conversely, scare each other away, and also warn of danger.



    How bed bugs use their eyesight

    Just because bed bugs have poor eyesight doesn't mean they don't have it at all. How bedbugs use visual perception when they find prey was studied by Narinderpal Singh and his team at the University of New Jersey.

    The task of this team of scientists was to analyze the reaction of bed bugs to different colors and vertical objects, as well as to assess their ability to see in low light levels. For this, several experiments were carried out.

    Color perception

    In one of them, bed bugs were placed in the center of a round flat plastic bowl with a rim (diameter 11.5 cm), on four sides of which there were artificial shelters of different colors. The shelters were folded pieces of paper with excrement and bedbug skins to simulate natural conditions.

    The insects had 4 hours to choose a place, after which the researchers counted the number of bugs in each shelter. All paper shelters were divided into two combinations, each of 4 colors: black - white - green - yellow and red - blue - green - yellow. After four repetitions of the experiment for each combination, the scientists calculated the color preferences of the bedbugs as a percentage.

    Here are the charts with the results:

    When it became clear that the bugs prefer black and red among the presented colors, scientists tested each of these two colors separately. Now in the bowl opposite each other there were two black shelters and two white ones (as controls) and the same combination in a combination of red and white. The experiment was again carried out in the mode of 4 hours and 4 repetitions.

    Here are the results:

    Bed bug preferences confirmed.

    However, it is impossible to know for sure whether their vision really distinguishes colors. Perhaps the bed bugs preferred black and red simply because those colors looked darker than the others. This would then mean that dark objects are more attractive to these parasites than light ones.

    Dr. McNeil of Union College in Lincoln, Nebraska, suggests that the choice of dark colors is due to the fact that the bugs tend to congregate in hiding places, to be near relatives. Hungry adult bugs have a brownish brown tint, and those who have drunk blood are dark red or almost black. It is also possible that red attracts bedbugs, as it is the color of blood.

    It is also important to note that the experiment was carried out in a white room, and, consequently, dark colors stood out more strongly against a light background. More research is needed to determine what role color contrasts play in bedbug vision.

    Response to vertical objects

    The next block of experiments was devoted to the question of whether vertical objects help bedbugs to navigate when searching for food.

    In a plastic tray (80×75×5 cm) representing the experimental site, special traps for bedbugs (in the form of round flat bowls) were placed. Traps were equipped with vertical objects in the form of brown and black paper tubes 30 cm and 15 cm high. These objects imitated furniture legs of beds and sofas. Also in one of the experiments, a rectangular object on a vertical leg was used - an imitation of a towering bed frame.

    When choosing, an empty trap or a vertical tube - more than 60% of the bugs went to the tube:

    It had a similar effect on parasites and a rectangular object:

    There was no difference between black tubes and brown insects. The height of the tubes (30 or 15 cm) also did not affect their behavior.

    These observations indicate that vertical objects standing out against a contrasting background serve as a kind of guiding pointers for bedbugs.

    Since the height of these objects did not play a role for them, this may indicate that they have flat two-dimensional vision. However, three-dimensional vision for bed bugs is not so important, because these insects cannot fly or even jump. To crawl, a flat visual image is enough.

    Under what lighting conditions can bed bugs see? 05 lux).

    0.05 lux roughly corresponds to the level of illumination of a bedroom during the night without the use of electric lighting

    In absolute darkness, the bugs did not distinguish between black and white colors, and also did not detect the presence of vertical objects. However, at an illumination of 0.05 lux, 70% of the experimental bugs chose black shelters, and 82.4% chose tube traps.

    Based on the results of this scientific work, it can be concluded that vision is an important auxiliary tool in how bedbugs find food. Parasites, of course, cannot see a person, but even at night they distinguish bright vertical objects, which they use as clues when choosing the direction of movement.

    How bed bugs navigate by surface texture

    While exploring how bed bugs find their prey, Narinderpal Singh also focused on studying the tactile response of bed bugs to different surfaces.

    The whole body of these insects, including the antennae and legs, is covered with hairs that contain the endings of sensitive nerve fibers that respond to touch - tactile mechanoreceptors . While searching for a victim, the bug stumbles upon different surfaces, evaluates them "by touch" and takes them into account when choosing a further route.

    In experiments, scientists covered the surface of the traps with different textures and then tested them on bed bugs.

    Three traps were pasted over with paper-based medical tape. Of these, one was painted with black leather dye, which penetrates deep into the material but does not change the texture of the surface, and the other was painted with a layer of black spray paint. The surface of another trap was a painted, roughly textured plastic, and the last one was covered with polyester felt.

    5 color-textural models of the surface were obtained: from smooth to very textured. Of these, two combinations of 4 textures were made. All models, except for white medical tape, were in black. Combinations of these models in experiments and the reaction of bedbugs to them can be seen in the diagrams:

    It is known that bedbugs prefer rough (paper, fabric or wood) surfaces to smooth ones (metal or plastic). Insects use their hook-like clawed feet to cling to and climb vertical surfaces.

    This study showed that even a slight difference in surface quality significantly affects their behavior.

    The texture of the medical tape ensures good adhesion of the bedbugs' feet to the surface. The combination of this texture with black color was to the liking of the insects. Spray paint made the surface smoother, and this is no longer so convenient for the movement of bedbugs. The bugs did not like the rough but hard surface of textured plastic at all, since their paws could not catch on it. Insects also did not appreciate coarse felt, probably because their claws can get tangled in too fleecy material.

    So, we have seen that different surface textures also indirectly affect how bedbugs find a person in an apartment. We can sum up.

    Comprehensive search engine

    Scientific studies have shown that bed bugs use a range of tools to search for food.

    If we compare them in terms of importance, then the ability to feel CO2 exhaled by us deserves special mention. Only this "device" works autonomously from the rest and turns on the very first, launching the entire search mechanism. Perception of CO2 sets the coordinates of the main target for the parasite, and only after that the search strategy is built. In how bedbugs find a person, this is the most important factor.



    Vision and tactile mechanoreception help insects find the best route. Thanks to these tools, the bug uses guiding visual cues and chooses the most convenient path. Sensitivity to temperature difference notifies the bloodsucker that he is almost at the target. The sense of smell seems to be the least involved in the process.

    Let's hope that the hard work of scientists will help develop affordable and effective bed bug traps and make our fight against parasites easier. 9(23) September 2016

  • “Smelling your way to food: Can bed bug use our odor?” // Journal of Experimental Biology 215 (Pt 4) February 2012
  • “Characterization of Antennal Olfactory System of the Bed Bug (Cimex lectularius) // Chemical Senses 35 (3) March 2010
  • “Role of Vision and Mechanoreception in Bed Bug, Cimex lectularius L. Behavior” // Public Library of Science 10(3) March 2015
  • “Behavioral Responses of Nymph and Adult Cimex lectularius to Colored Harborages” // Journal of Medical Entomology April 25, 2016

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    The smell for bedbugs is not the main thing

    Natalya Reznik
    "Trinity Variant" No. 8 (102), April 24, 2012

    It would seem that in our age of cleaning products, powerful vacuum cleaners and automatic washing machines, bedbugs can be forgotten, but no! Bed bloodsuckers often disturb residents of developed countries, the Internet is full of photographs of Europeans showing bitten places. So the fight against bedbugs is still relevant, but ineffective, because for many years people have not figured out which substances attract bedbugs and which ones repel. The smell of a person is complex and consists of about 400 components, among which scientists have not found a single obvious attractant.

    Experts from Lund University ( Lund University ) and the Swedish University of Agricultural Sciences ( Swedish University of Agricultural Sciences ) under the guidance of Professor Rickard Ignell ( Rickard Ignell ) entered the path of chemical warfare against bedbugs. Scientists have found that parasites are attracted to five volatile, i. e. odorous, substances secreted by the human body - four aldehydes and a ketone. Bed bugs looking for prey Cimex lectularius are guided by the body, which emits heat and carbon dioxide, as well as these odorous substances. At the same time, insects sensibly assess their capabilities and react only to low concentrations of volatile substances. If the smell is too strong, the bugs prefer not to get involved and leave.

    Back in the first half of the 20th century, experts found out that bugs find a person, focusing on the heat emanating from him and the carbon dioxide released, which was experimentally confirmed already in our century. However, at the same time, at 1932, Massachusetts researcher Ezekiel Rivnay ( Ezekiel Rivnay ) found that C. lectularius was attracted not only by the breathable warm body, but also by cold bits of animal skin. Obviously, bedbugs are also guided by smell. But what kind of aromas attract parasites, the scientist could not establish. According to Rivni, the smells of blood, muscles, subcutaneous tissue and cleanly washed skin do not affect the behavior of bedbugs, the smell of bile repels them, and the liver first attracts and then repels; The attractiveness of sweat depends on the stage of its decay. From tested substances C. lectularius sebum and earwax were the cutest.

    But "the smell of sebum" is a completely unscientific concept. Swedish researchers tested the reaction of bedbugs to individual volatile substances released by the human body. First of all, these substances had to be obtained. Eight volunteers took part in the study. No, they were not given to be eaten by bedbugs. These people spent two and a half hours in special bags, from which only their heads stuck out. A gas mixture free of CO 9 was slowly blown into the bags from above.0350 2 (20.9% oxygen and 79.1% nitrogen), and pumped out from below and extracted volatile substances from it. The researchers were able to isolate about a hundred components of the human smell and test their effect on the olfactory receptors of insects.

    Bed bugs sense odors through their sensilla located on their antennae. Sensilla are similar to hairs or spines, at the base of which there are receptors - neurons that perceive odors. With the help of a micromanipulator, the scientists connected microelectrodes to the sensilla and recorded the frequency of electrical impulses that occur in the receptors in response to the smell of the whole body and its individual components. It turned out that not all sensilla respond to the presented stimuli, but only one type of them - D-sensilla, or smooth spines. Moreover, their receptors are excited in response to only a few compounds - the unsaturated ketone sulcatone (6-methyl-5-hepten-2-one, β-methylheptenone) and four aldehydes (heptanal, octanal, nonanal and decanal). This kit surprised the researchers, since these aldehydes and ketones are secreted by the skin of any vertebrate. And to such volatile substances as geranilacetone or lactic acid, characteristic of humans, the bugs were indifferent. It turns out that they just want to drink warm blood, and it doesn’t matter from whom.

    Not all people excrete the full set of five substances. The researchers continued with the odors of two volunteers that contained all five volatile compounds, one that lacked heptanal, and one that lacked heptanal and octanal. These odorous extracts, as well as a mix - a mixture of the smells of all volunteers, they used in a behavioral test, which was supposed to show what kind of reaction stimulating odors cause in bedbugs - whether they can serve as a repellent or bait.

    For the behavioral test, scientists made a special device - a petri dish with a cellar. The cup was divided by a wall in half, and a filter with an odorous extract (stimulus) or control applied to it was placed in each half. An extract from artificial air blown through empty bags was used as a control. This structure was covered from above with a fine mesh, on which the insect was released. The researchers worked with virgin male and female bed bugs that were starved for 10–20 days. The movements of the bug were recorded by video cameras, and the observers then determined which half of the cup the insect spends more time on and at what speed it moves in this sector. If the bug rushes over the net and tries to bite it, then it is attracted by the stimulus under it, and if it spends more time in the control zone, the smell scares it away.

    It turned out that the reaction of bedbugs to smell depends on the concentration of volatile substances. Undiluted extracts repel insects, diluted 10 times they are indifferent, and diluted 100 times they attract, but not much. Moreover, the bugs prefer odors with lower ratios of sulcatone to aldehydes. And since the ratio of ketone to aldehydes in different smells is different, this explains why some people are more bothered by bedbugs than others.

    The researchers concluded that odor alone had little effect on bed bug behavior and only had a noticeable effect when combined with other factors: heat and carbon dioxide. In addition, the odorous stimuli to which bed bugs respond are non-specific. So while man and main host C. lectularius, insect receptors are not tuned to perceive our smells. Perhaps the reason for the low sensitivity and non-specificity of the olfactory system C. lectularius lies in the fact that the bug does not have to find its favorite host by smell, overcoming long distances for this. A person himself comes side by side, on a bedbug sofa, and the parasites find the object by the movement of air. And according to many researchers, bedbugs use their olfactory receptors for interpersonal contacts at a short distance, for example, when interacting with individuals of their own species.

    It turns out that chemical warfare with bedbugs is ineffective at this stage, scientists have not yet found odorous attractants. Their absence suggests that bedbugs can drink not only human blood, but also the blood of other vertebrates, such as rodents or birds. But for a person who finds himself in the same bed with a bug, this does not make it any easier.


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