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Cimex Lectularius: Common Bed Bug – All There is to Know


Reading Time: 12 minutes

Nature is lovely and can be scary at times, especially when we are thinking about tiny, blood sucking creatures like bed bugs. As it is, an infestation from a single species of bed bugs is enough to send chills down any homeowner’s spine.

Though tiny and small, these vampires can rob you of your sleep and leave you too tired, itchy and irritated to conquer a new day. Because of this, it’s scary to think that there are more than 90 known species of bed bugs. Keyword on known (there could be a bunch of other species that entomologists haven’t identified yet).

But there’s some good news. Not all of these species feed on human blood. Other species prefer animal and bird blood. That’s comforting, right? All the same, you need to learn about the different species and how to identify them. This will help you fight off a bed bug infestation in your home efficiently.

Note that different bed bug species are immune to different types of treatments, depending on what it has been exposed to over the years. So, rather than jumping in blindly, educate yourself and call in a professional to handle the infestation problem for you.

With that said, let’s jump right into it.

How Many Bed Bug Species are There?

As we’ve pointed out, there are about 90 known bed bug species. And since most of them fall under the same genus, they can be difficult to tell apart unless you are keen to study them and look out for the subtle differences.

In addition to having a similar physical appearance, they are also genetically related, which also means their feeding, mating, and reproduction processes are similar. They all leave bite marks.

The common bed bugs fall under a genus named Cimex. This genus, has more than 12 bed bug species under it. Bed bugs under Hemiptera are considered to be true bugs and not just normal insects.

Again, as we pointed out, only a few of these bed bug species feed on human blood. And in light of this, there are only two species that live up to the name ‘bed bugs’ as regular homeowners know them.

The two bed bug species are biologically referred to as Cimex hemipterus and Cimex lectularius. Their common names are tropical and regular bed bugs. The other bed bugs loathe human blood. For this reason, it’s rare to find them hiding in the seams of your mattress, furniture or bed.

Other species include swallow bugs and bat bugs. If we were to include these species to the list, the list would be very long. However, besides the Cimex genus, other genera that entomologists classify as bed bugs include;

  •       Cimex
  •       Ornothocoris
  •       Cimexopsis
  •       Hesperocimex
  •       Oeciacus
  •       Haematosiphon
  •       Primicimex
  •       Synxenoderus

According to entomologists, every species in the above genera feeds, reproduces and looks like normal bed bugs. However, they rarely (if ever) come close to humans. Moreover, some bed bug species are little known since there’s scarce information on them.

Only bed bugs that feed on humans are found in homes; close to their source of food. As such, only they can be classified as real bed bugs.

Species of Bed Bug

Since they are classified under the same genus, they are similar just like the other bed bugs are. To help you tell them apart, here is some information on each of the most common types.

Cimex Lectularius (Common Bed Bug)

This is by far the most prevalent bed bug in the United States and the world over. They have a rich history, and since 1980 their numbers have been growing steadily. Today, these bed bugs are found in many U.S states and some European countries as well.

If you have never come across bed bugs before, you are probably wondering what bugs you saw. Below is a rundown of a bed bug anatomy. How a common bed bug looks like (many bed bugs look the same with some minor variations).

How big is the common bed bug?

An adult common bed bug measures between 4mm and 5mm in length when it has not fed on blood. Once it has sucked you to its fill, it can measure up to 7mm long. The bodies of bed bugs can swell and stretch slightly to accommodate food.

To give you an idea of the size we are talking about, entomologists say that they are as big as apple seeds. They also have the same shape – oval-shaped abdomen and a tiny head.

What color is the common bed bug?

Here’s an interesting fact – bed bugs also look like apple seeds in color. They have a deep reddish-brown (more like the color of rust). Actually, the easiest way to describe the color is mahogany.

The bed bugs get the brown color from the thick layers of exoskeleton they feature. Speaking of layers, with every layer, the bed bug gets darker. It’s because of this that the nymph changes color from a transparent color to a reddish-brown as it approaches the adult stage. The red hue is gotten from the food it prefers – blood.

A bed bug that has just had a meal is bright red (brighter than unusual).

Body parts

Like all insects, the common bed bug has three body parts – head, thorax, and abdomen.

Head – the head of a common bed bug is tiny. The head has an eye on each side, and a sharp and pointed beat at the front. To pierce and duck blood from your capillaries, they have a long proboscis. When not in use, these specialized mouthparts are kept out of sight. Also, the common bed bug has a pair of antenna. They are short and are roughly the same length as their first pair of legs.

Thorax – after the head is a midsection (thorax). Though it is slightly larger than the head, it’s relatively small if you compare it to the abdomen.

Abdomen – The abdomen is 4x the length of the thorax and about twice in width. The abdomen is generally rounded. However, when it is hungry, it is flat from the side view, and when it’s full, the abdomen is elongated and becomes fatter.

Now, we should point out that the common bed bug’s body is segmented. There are two tiny and basic wings close to the thorax. These wings are functionless. Entomologists believe there was a time bed bugs could fly. Luckily, through evolution, they gave up this privilege. This can be explained through the ‘use and disuse’ theory of evolution taught in high school.

We should also point out that like normal insects, common bed bugs have six legs. Viewing a bed bug from above, the front pair of legs extend from the thorax while the second and third extend from its abdomen. Every leg has a joint and a foot with tiny hooks that it used to grasp onto the human skin.

The difference between a male and female bed bug

Though it is tricky, it is possible to pick out a male from a female bed bug. The difference is in their abdomen. A female bed bug is usually rounder than a male bed bug. A male bed bug has a slim and elongated body when it hasn’t fed. But you have to be keen to notice this difference.

The most obvious difference is the abdomen tip. For a female bed bug, the abdomen tip is round and smooth. On the other hand, a male bed bug has a pointy tip. This is where the penis is located.

Identifying a common bed bug nymph

A nymph is a bed bug that hasn’t grown into an adult bed bug. It is still going through the life stages, eating, and molting.

When a bed bug hatches from an egg, it becomes a nymph.

The common bedbug nymph measures about 1.5 mm in length and is off-white. All bed bugs go through five nymph stages, which entomologists call instars.

The nymph shell is thin. Because of this, you can see through their stomach. When the bed bug hasn’t fed, the stomach is seen as a tiny dark dot. When it has fed, it is engorged and bright red. Generally, a nymph looks like an adult bed bug. However, it differs in color and size. At every stage, the nymph will get bigger and a shade darker. It will go from cream to honey, pale brown and mahogany. Each shift from one stage to the next is characterized by a molt, which accommodates the new size.

Common bed bug molt

If you can identify a common bed bug, you can identify its molt. Bed bugs shed their skin in one go. As such, the molt looks exactly like the bed bug. You can see the legs, head, thorax, and abdomen.

However, it has a pale color; it’s coarse and empty. When you poke it, it doesn’t run away (this is how you know you are dealing with a molt).

Common bed bugs hide in dark and enclosed spots for safety. Entomologists say that bed bugs have nocturnal tendencies as well. The spots they hide out in include cracks in the furniture, floorboard, mattresses and underneath furniture.

Cimex hemipterus – Tropical Bed Bug

These bed bugs look like common bed bugs. However, there are slight differences. The main difference is the fact that tropical bed bugs (as you would guess from the name), love tropical regions where the weather is warm.

They specifically love areas that are around 30 degrees south and north of the equator. Because of this, this type of bed bug is most common in South America, Africa, and Asia. But from time to time, you can find them in locations in the US that are warm enough.

As for anatomy, this bed bug resembles the common bed bug in length, color, and shape. The symptoms of infestation are also similar. Like the common bed bug, tropical bed bugs also leave behind molts and feces. The physical variations are minimal and can’t be noticed by the naked eye. You need to use a microscope or call in an experienced pest controller to identify the species that has infested your home.

Also, like common bed bugs, the tropical bed bugs love to hide out in tiny enclosed and dark places. Spaces between the bed joints and in the seams of the mattress are a favorite. In the U.S, tropical bed bugs come in second based on prevalence. For some time, between 1940 and 1980, they had almost become extinct because homeowners were using an efficient chemical – DDT. This chemical also worked against common bed bugs as well.

However, the tropical bed bugs made their return and debut in Florida. The first people to identify them at the time were researchers from the Florida University in 2016. Since then, they have spread in all of the U.S. The area down south has temperatures enough to accommodate their needs.

Bird and Bat Bed Bugs

Bat bugs are considered to be the original bed bugs. And if you think about it, bats are related to vampires, and bed bugs feed on human blood – it all makes sense. But seriously, though. Cimex hemipterus and Lectularius have gone through the evolution process. They went from bugs feeding on bats to feeding on humans. Because of this, they are indistinguishable from the common and tropical bed bugs.

How did these bed bugs make the shift from feeding on bats to humans? Well, eons ago, when people turned caves into homes to shield themselves from the weather elements, bed bugs changed their diet to human blood. Over time, they developed a sweet tooth for human blood, and when we moved to live in houses, they moved with us.

Now, though the bats prefer feeding on bats and hang around in caves where they are close to their food when the opportunity presents itself, they will bite and feed on humans as well.

In the 21st century, bat bed bugs come into contact with humans if a building or your home is infested by bats. But even when there are bats in a building or house, the bat bed bugs will only feed on humans once the bats migrate or are removed and the bat bed bugs are forced to survive on human blood.

The bat species are found in Africa, eastern and some western parts of the U.S. the most common types of bat bed bugs include Cimex pilosellus, Cimex adjunctus, and Cimex pipistrelle.

The Cimex adjunctus is specifically known to feed on the insectivorous bats like the brown bat. The bed bug lives in the tiny cracks in dark bat caves. When the bats sleep, they come out to feed. Occasionally, they hitch a ride on the bats’ wings when they are flying around. But this is a rare occurrence.

But here’s the most unfortunate bit for this type of bed bug – their preferred prey is insectivorous. As such, they feed on insects, including bed bugs.

Oeciacus Hirundinis and Vicarius – Swallow Bugs

These bed bugs are classified under Cimicidae. However, unlike the above bed bugs we’ve reviewed so far they fall under Oeciacus. Because of this, entomologists consider them to be bed bugs even though they do not feed on human blood.

They are similar in appearance to the common bed bug in many ways than one. The only notable difference is the fact that the swallow bugs have long hairs on their shell. But besides this, they have the same size, shape, and color.

Like bat bugs, the swallow bugs prefer feeding on birds than on humans. They specifically love Swallow blood, hence the name ‘swallow bed bug.’ Unlike bats that live in dark space, swallows live in nests. The swallow birds look like the wasp nests. They are enclosed and love dark spaces, especially when the birds are growing. These spaces help to keep them strong.

The swallow bed bugs prefer barn and cliff swallows. And since bed bugs love enclosed and dark spaces too, they feed on the birds. On the other hand, Oeciacus vicarious live in the nests with the bird and suck their blood. The Oeciacus hirundinis (the European swallow bug) is the same as well.

And just like common and tropical bed bug infestations, the swallow bug infestation can get out of hand. When this happens, the nestlings will have to leave the nest before their time. The adults will soon follow.

And just like the common bed bugs, swallow bugs cannot survive in nests without food for more than a year. Over the years, they’ve been forced to adapt when the swallow birds migrate.

Hesperro Cimex Sonorensis and Hesperro Cimex

These two-bed bugs fall under a different genus – Hespero cimex. These two species can be found on the west coast or the Midwest United States. They love to feed on wild animals, including birds and bats. According to research, they love the pygmy owl blood (https://www.jstor.org/stable/20060080?seq=1#page_scan_tab_contents).

Given their vast prey, they don’t have a specific habitat. They generally move to where their prey lives. And in some cases, they can hide inside cactus and lay in wait for bats to arrive when they come to roost.

Haematosiphon Inodorus

This bed bug is popular as the Mexican chicken bug. They are similar to regular bed bugs. However, they have a preference for chicken. If you rear poultry in your land, you might have seen them crawling on the walls or the ground.

In the 21st century, bed bugs are also likely to suck chicken blood, just like the Mexican chicken bug is. You can control and put an end to the Mexican chicken bug like you would regular bed bugs.

Cimexopsis Nyctalis

They are popularly known by the name chimney swift bed bugs. Though they look like common bed bugs, they have longer legs. Also, they look like common bed bug in shape, size, and feeding preference. But there are some notable differences between the two.

The chimney swift bed bugs are not predominantly nocturnal. They can either feed at night or during the day, whenever the hunger kicks in.

They can climb on slippery and sheer surfaces, and love living in the walls and avoid seam mattresses.

Although they feed on the chimney swifts, when push comes to shove, they can make their way down the chimney and into your bedroom for a quick snack.

Ornithocoris Toledoi and Pallidus

These are bed bugs that also love bird blood. They have a special preference for Martian birds. And just like the Mexican chicken bug, these bed bug types can also feed on your poultry.

The differences are minor. The Ornithocoris Toledoi is dark brown while the Ornithocoris Pallidus is a shade lighter. Aside from this, there is very little information on these genera.

Buchimex Chilensis and Primicimex Cavernis

These two-bed bugs look very similar. They are both found in South and Central America. They too are larger than common bed bugs. They have thicker and longer legs that resemble those of a spider than anything else. Also, they are about ¾ inches longer.

In Central parts of America, the Primicimex Cavernis as a preferred habitat – in cacti where bats roost. The cacti the bats live in have holes made by woodpeckers. The Primicimex Cavernis also lives in the hollow space and feeds on the bats. You can also find the bed bugs caves as well.

Synxenoderus Comosus

Aside from the fact that it lives in the US, there are very few facts available on this bed bug type.

Other Types of Bed Bugs in Genus Cimex

The bed bugs that we have covered above are a portion of the ones available. There are loads more that live in the US and other parts of the world. Below is a shortlist of other bed bugs in the genus:

  • Cimex brevis – this is a rare bat bug. It is found in North America.
  • Cimex emarginatus – this is a type of bat bug that is found in Southern/Eastern Europe
  • Cimex latipennis this is a bat bug that is from Northern Pacific America
  • Cimex japonicas – this is a bat bug with its roots in Japan
  • Cimex pilosellus – this is a bat that is found in Canada and Northern U.S
  • Cimex incrassatus – this is a rare bat bug type that is found in North America
  • Cimex antennatus – this bat bug species is found in Pacific North America
  • Cimex columbarius – this is a bed bug type that infests bird nests especially pigeons

All of the above-listed bed bug species resemble regular bed bugs. Again, it is impossible to differentiate them. However, it’s improbable that you’ll find one in your home. They love nests and caves which are available in nature.

However, it’s not easy to come into contact with these caves and nests. Also, it’s important to note that some of these bugs were common eons ago than they are today.

Bedbug species identification

The two bed bugs that feed on humans are the common bed bug and the tropical bed bug. Anatomically, they are nearly identical. It’s therefore difficult to differentiate them without the help of an expert. It needs a microscope. The main differences between the two include;

  • Pronotum size. The upper section of the body is called the pronotum. The tropical bed bug’s pronotum is wider and longer than in the common bed bug. It also has an upturned shape.
  • The pronotum of the common bed bug is u-shaped.

Behavior wise, there are two main differences you can understand. Tropical bed bugs lay few eggs in comparison to regular bed bugs. As such, their adults don’t feed frequently. Also, tropical bed bugs grow faster than common bed bugs.

Why is species identification important?

So these bed bugs look, feed and behave in the same way. Heck, they even leave similar bite marks. So why should you know how to distinguish between the two? Well, in all honesty, not so much research has been done between the species. As such, there are not many treatment options. However, knowing the type helps in determining the right approach to take and approximating the level of infestation.

And with that, you are now ready to take on your bed bug infestation. You might not use the above information yourself, but it will come in handy to help you understand the treatment methods the exterminator employs and whether it is going to be effective in ridding your home of the bed bugs.