How Big Are Bed Bugs Compared to Other Bugs?

Written by Rebecca Bales
Updated: October 12, 2022
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Key Points

  • Adult bed bugs can be from one eighth of an inch to one-quarter of an inch long. That is 4 to 7 mm in length.
  • An adult bed bug is rust or reddish in color.
  • A series of tiny red or dark brown spots on a sheet or cushion is one sign of this pest infestation. These are spots of blood.

How big are bed bugs compared to other bugs? An adult bed bug grows to be about one-quarter of an inch in length. Some bugs are longer than bed bugs while others are shorter.

Of course, there are other bugs that are about the same size as a bed bug.

Discover several size comparisons between bed bugs and other types of bugs. Also, learn other facts about these pests such as the size and color of their eggs and babies.

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How Big Are Bed Bugs?

Adult bed bugs can be from one-eighth of an inch to one-quarter of an inch long. That is 4 to 7 mm in length. They are oval-shaped with six legs. These insects have an appearance similar to a watermelon or an apple seed.

Baby bed bugs are known as nymphs. Nymphs molt their exoskeleton several times as they grow into adults. A newly hatched nymph is one and a half millimeters long. It continues to grow in length as it molts its exoskeleton. Nymphs are white or sometimes ivory in color.

The eggs are even smaller than nymphs! Eggs are oblong, white, and measure one millimeter long. The actual size of an egg can be compared to a grain of rice. They are easiest to see on a dark surface using a magnifying glass.

What Color Are Bed Bugs?

An adult bed bug is rust or reddish in color. One of the most interesting facts about this insect is its color changes depending on whether it has just taken in nourishment. The nourishment of a bed bug is human blood.

The body of a bed bug becomes darker after it drinks blood. Furthermore, the actual size of an adult change after it eats as well.

close up of bed bug
Adult bed bugs can be from three-sixteenths of an inch to one-quarter of an inch long.


Does the Size of a Bed Bug Change After It Eats?

Yes. The actual size of this insect becomes larger after it drinks blood. With the intake of blood, its body becomes elongated and takes on a cylindrical shape.

What Bugs Can Be Mistaken for Bed Bugs?

Bat bugs are closely related to bed bugs. This is why these insects are easily mixed up. Both of these insects are parasites and live on blood. They are both brown with a similar body shape. Plus, adult bat bugs can grow to one-quarter of an inch long. In other words, it takes a very close examination to distinguish between these bugs.

One thing to note is a bat bug’s abdomen has a pointed end while a bed bug’s abdomen is rounded. In terms of behavior, bat bugs drink the blood of bats whereas bed bugs live on human blood.

Booklice are sometimes mistaken for bed bug nymphs. They both have white bodies that are very difficult to see on a white surface. But booklice are longer sometimes measuring up to six millimeters. Booklice are found in many of the same places as bed bugs. For instance, booklice live in furniture, on window sills, beneath floors, in ceilings, and even behind sections of wallpaper where mold is present. They can even live in potted plants!

Fleas are sometimes confused with bed bugs. They are parasites that are also reddish-brown in color. But, while fleas can crawl and jump, bed bugs are only able to crawl.

Cockroach nymphs are sometimes mistaken for adult bed bugs. Though a cockroach nymph starts out as white, its skin becomes darker within a few hours of hatching. At this point, it takes a careful comparison to tell these two insects apart.

Keep in mind the body of a cockroach nymph is cylindrical whereas an adult bed bug has an oval shape. Also, the antennae of a cockroach nymph are a little longer than a bed bug’s antennae.

A spider beetle bears some resemblance to an adult bed bug. Both insects have six legs, antennae, and dark brown bodies. However, a spider beetle’s body is elongated. Furthermore, a spider beetle nourishes itself on crumbs and dropped food instead of blood.

Ticks can also be mistaken for bed bugs. Yes, both insects are parasites. Their bodies become larger after drinking a meal! In addition, both the tick and the bed bug have a dark brown, oval-shaped body. However, a tick’s body is flatter than the other insect’s body.

Normally, ticks are found outdoors in wooded areas while the other pest is found indoors. Also, ticks have eight legs and bed bugs have just six. Furthermore, a tick can bite or physically attach itself to an animal or a human to drink blood.

Are Bed Bugs More Destructive Than Other Bugs?

No. Unlike termites or carpet beetles, bed bugs don’t chew through walls, carpeting, or wooden furniture.

How Can You Tell the Difference Between Bed Bugs and Other Bugs?

Of course, looking at the features of a bed bug and another insect can help you to determine the difference. You can also look at the behavior of each bug.

A comparison of the behavior of a spider beetle and a bed bug reveals some differences. For one, a spider beetle would likely be found in a kitchen whereas a bed bug can be found in most rooms in a home. Why? Because while a bed bug drinks blood, spider beetles live on crumbs and other food spilled in cabinets or on the floor.

A comparison of the behavior of a flea and a bed bug reveals a number of differences. For one, a flea can jump while a bed bug isn’t able to jump. Second, though fleas drink blood, they are normally found on dogs, cats, and other pets while bed bugs drink the blood of humans. If you have a hard time identifying bed bugs, we suggest the Harris bed bug traps.

They come in a pack of 20 and make it easy to capture bed bugs and examine them more closely to see if you have a true bed bug infestation, or simply another insect problem.

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Is a Bed Bug Bite Harmful to Humans?

Yes and no. Thankfully, their bites are not poisonous. But they can cause irritated, itchy skin on various parts of the body. It’s a good idea to wash the bite area with warm water and mild soap. Anti-itch ointment can help to relieve irritation and redness.

Bedbugs can bite any part of your body. However, they’ll normally bite areas of skin that are exposed while you sleep. This includes your face, neck, arms, and hands.

Can You See Bed Bugs?

Yes. Despite being very small, adult bed bugs can be seen with the naked eye mostly due to their dark color. The heat from a hairdryer can cause adult bugs to crawl out of a piece of furniture, a bed frame, or from beneath an area rug. Incidentally, heat is a tool exterminators use when treating a home for these pests.

Nymphs and eggs are more difficult to see with the naked eye. This is due to their light color and extremely tiny size. Consequently, exterminators have special equipment they use to look for visible evidence of these pests.

What Are Signs of a Bed Bug Infestation?

A series of tiny red or dark brown spots on a sheet or cushion is one sign of this pest. These are spots of blood. They get on sheets and cushions when bed bugs are partially smashed. Just imagine someone being bitten by this pest in their sleep and rolling over just as the bug was trying to get out of the way!

Tiny black spots left behind on blankets, sheets, pillowcases, and other surfaces are the feces of bed bugs. These are very hard to see and may only be noticed when someone is putting sheets and pillowcases into the washing machine for cleaning.

In addition, bed bugs come out at night to look for nourishment (blood). This makes sense because most people are asleep in their beds during the night. So, it’s possible you may never see any of the pests. But bed bug bites are certainly a sign of these pests in a home.

bed bugs on wood furniture
While bed bugs can sometimes be found in the hair, they are most commonly found on mattresses and furniture.

© Lanciano

Why Are Bed Bugs So Difficult to Get Rid Of?

Bed bugs have a reputation as being very difficult to get rid of. This is mostly because they can hide almost anywhere in a home. Some typical hiding places include furniture, behind electrical plates, in the seams of cushions as well as inside mattresses and bed frames.

So, a house must be thoroughly treated in order to get rid of all the eggs, nymphs, and adult insects in hiding. If a few eggs or nymphs are left alive after an exterminator’s treatment, it potentially means a re-infestation of the home. This would require yet another treatment to get rid of all traces of these pests.

These pests also reproduce very quickly. One of the most amazing facts about this insect is a female can lay from 250 to 500 eggs in her short lifetime. Plus, she can lay eggs practically anywhere in a home. The incubation time for these eggs is six to ten days. All of this means that a couple of bed bugs in a home can quickly turn into an infestation!

Finding hundreds or perhaps thousands of bed bugs hiding in a home can be a very tough challenge.

We recommend a comprehensive approach to getting rid of bed bugs that includes vacuuming, using spray, traps, blockers, and even a new mattress.

Up next…..

The photo featured at the top of this post is © Dmitry Bezrukov/

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About the Author

Rebecca is an experienced Professional Freelancer with nearly a decade of expertise in writing SEO Content, Digital Illustrations, and Graphic Design. When not engrossed in her creative endeavors, Rebecca dedicates her time to cycling and filming her nature adventures alongside her supportive partner. When not focused on her passion for creating and crafting optimized materials, she harbors a deep fascination and love for cats, jumping spiders, and pet rats.

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