How Small Are Bed Bugs?

  • Written By Dan Edwards on January 3, 2018
    Last Updated: December 28, 2020

The truth is, there’s a lot of misinformation floating around about how to identify bed bugs versus other bugs, and knowing their size can make a big difference in proper identification. That’s why I’ve made it my mission to gather all the most accurate information about bed bugs and make it available to people who need the facts.

What I’ve discovered is that yes, you can spot and identify bed bugs in your home. Knowing what size of insect you’re dealing with is a good starting point. Once you realize how small bed bugs are, you’ll be better equipped to use the right methods for finding them and treating your home. Get the rest of the facts by reading on.

How Small Are Adult Bed Bugs?

One of the reasons that bed bugs are so hard to find is that they tend to only come out when you’re sleeping or otherwise distracted, but another reason why is that they actually are quite small. In fact, adult bed bugs are only around 4 to 5 millimeters in size.

Bed Bug Size
CC Image courtesy of British Pest Control Association
CC Image courtesy of British Pest Control Association

To visualize just how small that is, a single lentil is a little over 6 millimeters. The adult bed bug is just smaller than a lentil.

Now, the thing about finding and identifying bed bugs is that you may not ever see the adult bugs. When that’s the case, you need to know how to identify bed bug nymphs and eggs, as well as other signs of bed bug activity.

Feeding time

Interestingly, bed bugs do change size with each feeding. After ingesting blood from a host, the insects will fill up and go from a flat shape to a more filled out shape. However, because bed bugs come out at night and crawl back to their hiding places quickly after feeding to digest their blood meals, you’re more unlikely to see them in their fully-fed state.

How Small Are Baby Bed Bugs?

Baby bed bugs are called nymphs, and they look somewhat different from older bed bugs. Their color is more translucent. Also, baby bed bugs are smaller than the adults. Adult bed bugs are already quite difficult to find because of their size, and the nymphs’ translucent color along with their even smaller diameter makes them even more difficult to spot.

CC Image courtesy of louento.pix

Whereas an adult bed bug is close to the size of a lentil, baby bed bugs, depending upon their stage of life, may be smaller than a sesame seed, which is about 3 millimeters in size. Baby bed bugs range from 1.5 millimeters to 4 millimeters.

Bed bugs move through five nymph stages before reaching adulthood. They grow with each stage, as well as shedding their outer skin to allow for growth. You may see these molted skins on sheets or furniture–a sign that you have baby bed bugs in your home. On average, bed bugs grow about half a millimeter with each molt.

Bed Bug Shells
Bed bug casings – CC Image courtesy of louento.pix

As with adult bed bugs, baby bed bugs can also change size slightly after feeding.

CC Image courtesy of AFPMB

How Small Are Bed Bug Eggs?

You may have guessed that bed bug eggs are even smaller and even more difficult to spot than the adult bed bugs or nymphs, and you’d be right. Despite being so small, you can see bed bug eggs with the naked eye. They are about the size of a poppyseed, around 1 millimeter.

Bed bug eggs – CC Image courtesy of British Pest Control Association

If you happen to find a bed bug nest, you may be able to see the eggs with the aid of a bright flashlight. The eggs are also pearly white in color, and they will have eye markings on them if they are more than 5 days old.

Bed Bug Eggs
CC Image courtesy of AFPMB

What Do Bed Bugs Look Like?

If you’ve found small bugs that fit the size descriptions here and you’re trying to figure out for sure if they are bed bugs, the good news is that bed bug nymphs and adult bed bugs look pretty similar to each other. This is especially true for the older nymphs as they are reaching adulthood themselves.

Adult bed bugs are a rusty or brownish color, and they look flat and oval if it’s been a while since they’ve fed on blood. Once they’ve eaten, their body takes on a fatter, more elongated shape, like a cylinder. Their color also changes after feeding, becoming redder.

CC Image courtesy of AFPMB

The nymphs are similar in shape, though smaller, and their coloring can be white or yellow and translucent if they are young.

Recently-Hatched Bed Bug Nymph – CC Image courtesy of AFPMB

Are Small Bed Bugs Hard To Find?

Small bed bugs can be hard to find, but with the right strategy, it’s not impossible. Bed bugs and their eggs are typically going to be found close to a source of blood, and because they prefer human blood over that of other animals, their hideout locations are at least somewhat predictable. After all, they wouldn’t be called bed bugs if they weren’t often found in beds.

Knowing likely locations will make finding the tiny pests easier. Look in cracks and crevices around places where you tend to sleep or sit still for long periods of time. That means you should check under the edges of mattresses, under couch cushions, and under chair cushions. You may also want to look at the joints on furniture frames and the cracks along baseboards.

CC Image courtesy of louento.pix

You should also check any luggage that you traveled with to ensure you don’t bring bed bugs with you after a trip. Using a flashlight can make this task much easier.

You may find cast off outer skin layers from when the nymphs molt and grow. These can be found outside the hiding area, in places where bed bugs have been active and feeding. Finding the molted skins is a good indication that you have a fairly large infestation and it’s time to find the hideout.

How To Get Rid Of Bed Bugs With DIY Treatment Methods

Hiring pest control professionals can be costly, and while it’s usually the best option, there are some preliminary steps you can take to get rid of bed bugs yourself.

1. Carefully bag and wash all of your bedding and clear any clutter around the room. Bed bugs love to hide in piles of clothes, so remove these and wash them before you start cleaning.

3. Use a high-powered vacuum to clean around the bed to take care of stray bugs and eggs. Using a vacuum with a HEPA filter is vital to ensure bed bugs cannot escape once captured. The Shark Navigator Upright Vacuum easily ticks all of the boxes while remaining lightweight and easily maneuverable.

4. Use a specialist, non-toxic bed bug spray to clean your bed-frame, headboard, and surrounding furniture. Bed Bug Patrol Bed Bug Killer is a completely natural spray that has a reported 100% kill rate against live bed bugs in controlled tests, and most importantly, it’s child and pet-friendly.

5. Pull your bed away from the walls and place bed bug interceptor cups under each leg. These will isolate your bed and help to prevent the spread of bed bugs. Additionally, interceptors can serve as tools to help you track progress. Ideally, the interceptors should contain fewer bed bugs every time you empty them. My favorites are these Bed Bug Blocker Interceptor Traps.

6. Using a bed bug mattress protector to encase your mattress will either help to save it if it’s yet to be infested, or otherwise keep bed bugs trapped in and around it until they eventually die of starvation. My favorite is the SureGuard Mattress Encasement which is thick, strong, and will help to stop bed bugs of all sizes from getting to, or from, your mattress. A SureGuard Box Spring Encasement is also available.

7. If you wish to be extremely thorough, specialist bed bug heaters can be purchased to raise household items to a temperature that is sure to kill all bed bugs and eggs. ZappBug is the most popular option, and is designed to automatically reach the all-important killing temperature to eradicate all stages of the bed bugs life cycle. Large and small versions are also available.


Yes, bed bugs are really small. That being said, small bed bugs can still be found and gotten rid of. You just need to be careful, vigilant, and most of all, you must feel like you’re in control of the situation.