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Bed Bug Anatomy: 17 Facts on Biology and Behavior


Reading Time: 9 minutes

Bed bugs are insects that belong to the Cimicidae family. These bloodthirsty parasites are known to be hematophagous. Blood is important for their development as well as reproduction.

A bed bug goes through 5 stages of development which are known as instars. They need blood for almost every instar.

With a good supply of blood, it should take a bed bug about 45 days to develop from an egg to an adult. If the blood supply is shaky, a bed bug could take longer to fully develop or die.

Bed bugs are a menace to homeowners. One of the reasons why these parasites are hard to deal with is their elusiveness. These creatures are well adapted to different environments and hide extremely well. They crawl out when you are asleep, feed on you, and you can’t even tell they were there. For this reason, it becomes tremendously difficult to eliminate them.

This doesn’t mean that it is impossible to get rid of bed bugs. But to defeat an enemy, you need to first know how they operate. In this case, it is imperative that you become well acquainted with the biology and behavior of bed bugs. Such information can help you come up with an effective pest control strategy for these pesky pests.

In this article, we are going to exhaustively reveal to you everything you need to know about the anatomy and behavior of bed bugs. This includes their different body parts, what they use to pierce through your skin and feed on you, some of their behavioral traits, why they are hiding and seek champs, and so on. Hopefully, at the end of this piece, you will have learned how to crack these creatures cryptic armor and kill them.

Here are 17 facts on the biology and behavior of bed bugs;

1. Bed bugs are small in size

An adult bed bug is about 4 to 5 millimeters. When fully fed, it becomes engorged and can stretch up to 7 millimeters. A bed bug’s size and shape are likened to an apple seed. Bed bugs are oval-shaped and flat.

A bug’s size is crucial to its survival. This is because it allows it to hide in narrow cracks and crevices. If you think a particular crack is too small for these creatures, then you are mistaken. You’d be surprised to find hundreds of these creatures in an extremely narrow crack.

The flat shape is also ideal for their hiding. That is why they can easily fit in rather narrow spaces and other places where their host can barely reach them. For this reason, some of the bugs control methods don’t turn out to be effective as expected, mainly because they can’t penetrate inaccessible harborages.

2. Bed bugs are supremely sensitive to movement

Bed bugs are always alert while in and out of their harborages. This can be majorly attributed to their compound eyes. Each eye has numerous repetitive optical units which are known as ommatidia. With these types of eyes, bed bugs sensitivity to movement is impressive.

If you happen to move as a bed bug is feeding on you, it takes off immediately because its eyes record all the movements, no matter how subtle it is.

Your movement doesn’t necessarily discourage bed bugs from feeding on you. These parasites are intelligent. They may wait for you to stop moving, and resume feeding.

3. Bed bugs have six legs

Like most insects, a bed bug has six legs. All its legs are attached to the thorax to facilitate movement. Their legs are well adapted for swift crawling. Though bed bugs are just but tiny insects, their crawling speed is fascinating. These pests can crawl up to 4 feet a minute at top speed. That is why you may sometimes encounter a bed bug but have no chance to smash it.

Besides that, they have claws that assist them to have an exceptional grip on rough surfaces. Nevertheless, smooth surfaces such as windows are remarkably challenging for bed bugs to crawl on. The claws also come in handy during feeding. A bed bug uses its claws to get a tight grip on its host.

4. Bed bugs use their proboscis to pierce through blood vessels

Bed bugs get their protein from the host’s blood. Whenever they infest your household, you can be sure that their main agenda is getting a blood meal. These creatures know how to go about their business secretly. They will leave their harborages when you are sleeping soundly, crawl to your bed and feast on you without waking you up.

The only reason you will know that these filthy parasites visited you at night is the itchiness on your skin which results from the bites. But why don’t you feel it when they are biting you? And what do they use to suck your blood? Well, bed bugs are well equipped. They’ve got everything they need for a feeding session that lasts about 3-10 minutes.

As part of the bug’s anatomy, there is a small tube known as a proboscis that bed bugs use to suck blood from their host.

When the bed bugs are preparing to feed, their proboscis elongates and injects an anti-coagulating agent that forms part of its saliva in your skin. This is coupled with a numbing chemical. The anesthetic ensures that you don’t feel any pain when the bed bug is feeding. It is the reason why it is almost impossible to catch a bed bug in the act.

Bed bugs don’t use the same stylet to inject the anti-coagulant and feed. They have two stylets; the maxillary and mandibular stylet. One injects the numbing agent and the anti-coagulant, while the other one draws blood from the host.

5. Bed bugs’ antennae act as sensors

A bed bug has a strong sensory ability, thanks to its antennae. The bed bug antennae are segmented into four parts. Each antenna is estimated to be as long as half the parasite’s body. These are not just antennae, they have a special function. They act as sensors, which lead the bed bug to its host.

Bed bugs have strong sensory tendencies. They can detect the presence of a potential host from 3 feet away. Usually, they will sense the heat and the moisture that your body emits while you are asleep. Additionally, they have a high affinity for CO2. Whenever they detect a certain degree of carbon dioxide, they know it’s time to approach the host and feed.

6. Bed bugs abdomens have staggering 11 segments

A bed bug has three body parts just like any other insect. This includes the head, thorax, and abdomen. It also has two antennae, two eyes, and six legs. Each of these features has a unique function.

Bed bugs may appear small in size, but their abdomens have 11 segments. As if that’s not enough, the segments expand as the creature feeds. This allows them to suck enough blood from the host. As they fill up with blood they may appear to be a little bit bigger.

A well-fed bed bug goes back to its hiding place. The blood meal is enough to last these pests several days. This could range between 7-10 days. Therefore, bed bugs remain in their harborages a considerable amount of time digesting the blood meal. They will only come out when they are hungry again.

If you think that you will enjoy a good night’s sleep for a few days as these parasites rest, you are wrong. There can be thousands of these bloodsuckers in your house. As some digest the blood meal, others will come out and wreak havoc on your body. There is no way that all of them will be full at one point.

By looking at their abdomens through a microscope, you can differentiate between a male and female bed bug. Normally, a female bed bug has a somewhat rounded tip while the male has a pointed tip.

7. Bed bugs have wing pads

One  of the body parts of a bug that has no use include the wing pads, which are commonly referred to as vestigial wings. This means that they are underdeveloped wings, and thus bed bugs can’t fly.

However, there is an explanation behind the wing pads and lack of flight in bed bugs. The chances are that their ancestors could fly. Over the years, the insect adapted to new habits that didn’t need them to fly. As a result, there was no need for the wings to fully grow hence the wing pad. You probably can’t see the wing pads with your naked eyes, but you can use a magnifying glass to identify them.

8. Bed bugs are rusty brown

Color is one of the most important characteristics when it comes to identifying a bed bug. Nonetheless, a nymph has a different color from an adult bug. At first, it has a somewhat translucent white color. As it feeds and grows, it turns to red due to the color of the blood meal. Later, as it reaches adulthood, the color becomes reddish-brown. This is the adult’s bed bugs’ color.

9. Bed bugs copulation takes place through traumatic insemination

Male bed bugs are sexually attracted to female bed bugs that are well fed. The attraction is even more if the female bed bug has recently fed. Unfed females may not get male suitors to mate with them.

A bed bug’s method of copulation is strange. It is something that you wouldn’t expect as it entails traumatic insemination.

The male bed bug has sharpened genitalia that aids copulation. On the other hand, the female has a soft abdominal section. This soft area makes it easy for the male genitalia to penetrate.

Usually, the male will identify a recently fed female. Then it will mount on the female firmly using its claws. It then pierces through the female’s cuticle using its intromittent organ and injects sperms.

The sperms are injected in the female’s mesospermalege (female’s organ tasked with migration of sperms). This process is known as traumatic insemination, and it is also associated with female bed bugs mortality.

Female bed bugs are likely to receive 5 traumatic inseminations after each feeding. This may be done by different male bed bugs. Although the female has a genital tract, the male doesn’t use it for insemination.

In a female bed bug’s lifetime, it lays over 120 eggs. At this rate of reproduction, a bed bug infestation in your household can easily go out of hand.

10. Bed bugs saliva harbors allergens

Most people have a bad reaction after a bed bug bite. This might happen a few days after a bug bite. Though bed bugs saliva is said to consist of an anti-coagulant as well as a numbing chemical, there are other xenogeneic constituents that don’t sit well with the human body. The xenogeneic constituents contain allergens that cause an unpleasant reaction on the host’s skin.

11. Bed bugs live in aggregations

Living in clusters makes bed bugs formidable parasites. According to recent studies, nymphs that are reared in clusters go through the stages of development much faster than the isolated ones. Bugs in clusters can steer away from dehydration much better than those in isolation.

Bed bugs that form aggregations survive longer when faced with difficulties such as the scarcity of the hosts than their counterparts.

The behavior of living aggregations has numerous disadvantages such as competition for mating partners. Also, it makes them much more discoverable by humans.

12. Bed bugs may leave aggregations in the face of danger

Aggregations provide a secure, homely feel for bed bugs. However, these creatures sometimes choose to leave behind their comfort zone. This happens if they find the living situation in the aggregation less hospitable, or when they perceive it as dangerous. Moreover, bed bugs prefer to live in dark harborages. If there is too much light, then they will move away to find a darker harborage.

13. Bed bugs have developed a thicker cuticle

Previously, bed bugs had a soft cuticle and could be easily killed using insecticides. DDT, an insecticide that had proven to be a lethal killer for bed bugs could easily penetrate through a bed bug’s cuticle. Unfortunately, that’s no longer the case.

Ever since the recent resurgence of bed bugs, traditional insecticides have been unable to eliminate these parasites. Studies have shown that, as a way of adaptation, bed bugs have developed a thicker cuticle that is proving to be impenetrable by the formerly potent insecticides.

14. Bed bugs release a distinct odor when disturbed

When bugs are disturbed, they release a particular alarm pheromone. The odor is likened to the coriander herb. This is why these parasites were commonly known as coriander bed bugs.

The odor is thought to come from their waste and it is often described as a musky smell.

Although humans can smell this odor, dogs do it better. No wonder dogs are popularly used to pinpoint bed bug hideouts during the pest management process. This has to be coupled with another supporting piece of evidence as dogs don’t always get it right.

15. Starved bed bugs die by drying out

Bed bugs are known to be some of the most resilient parasites. These disgusting creatures can live for months without a single blood meal. This means that if a house was vacated for a few months, then a new tenant took over, the chances are that they would have to deal with the bed bug menace.

When starved for a long time, bed bugs don’t die as a result of hunger. Instead, they die due to their bodies drying out. For this reason, you can expect a bed bug to survive even longer, especially in cold areas, without feeding.

Therefore, an isolated bed bug is likely to dry out and die much faster in an area where the air is characterized by low moisture.

16. Bed bugs like to hide during the day

It is hard to see bed bugs in broad daylight. At this time, these parasites are safely hiding in their harborages.  This is usually on rough as well as dry surfaces. Their feeding habits are somewhat nocturnal.  You have your dinner early and sleep through the night. Bed bugs have a different routine which is quite convenient for them. It includes feeding comfortably on you as you sleep at night, and rushing back to their hideouts at the break of dawn before you wake up.

17. Bed bugs can take a blood meal that is 6 times their body weight

Bed bugs are tiny insects that can punch above their weight in terms of feeding. These little vampires may be tiny, but their feeding capacity is astonishing. A bed bug will comfortably take blood that is 6 times heavier than its body weight in 3-10 minutes.  Its size grows within the minutes as its body gets engorged by the blood meal. Bed bug’s color seems to change from light brownish to a dark rusty brown when full of blood.

As you can see, there is a lot that makes a bed bug, one of the most feared parasites. But as we pointed out earlier, you need to know your enemy well if at all you intend to defeat them. Now that you know more about these bloodsuckers, you are just one step away from expunging them. And as always, it’s only wise to call in a professional exterminator whenever you discover an infestation of bed bugs in your office or home to get rid of them permanently.