What Do Bed Bugs Look Like

Summary: By now, we have all seen umpteen million pictures of bed bugs on TV, in the newspaper and on the web. But, for those still uninitiated and curious, I am going to give you some common objects to which to compare bed bugs.

All the pictures of bed bugs look similar. We know they are a light brown color and they turn dark red to mahogany after a hearty blood meal off the inside of your leg or the back of your arm or from where ever they decide to stop for a meal. We also know they have flattened bodies before they tie on the old feed bag, and swell up like mini-balloons once they have had their way with you. The adults can be easily seen with the naked eye, but they are still pretty small on the scale of all things living and you need to be looking in the right spots to find them.

2nd stage nymph, photo credits Univ. Florida

The adults which are sometimes referred to as "red coats," "chinches," or "mahogany flats", don't fly, but do have reduced fore wings, or hemelytra, that are broader than they are long, with a somewhat rectangular appearance.

They have six legs, two medium sized antennae, bulging eyes on the sides of their heads and horizontal body sections that look like armored plating, similar to a common pillbug that you might find on the window sill in a basement.

The sides of the pronotum are covered with short, stiff hairs. The pronotum, as defined in many dictionaries is the dorsal plate of the prothorax in insects. Still confused? The pronotum is the section on the hard shelled insect that is directly behind the head. Anyway, this section on a bed bug has short little hairs that stick out.

Now for the size. Lot's of misunderstanding about their measurements, so here is the size-o-meter for all us common folk who need to ask, “Does it fit in a breadbox?”, whatever that is. We'll start with the egg, so there is no need for discussion about which came first the bed bug or the egg.

Bed bug eggs are teeny, tiny. I know that's not very descriptive, but they are mostly invisible unless you are really focusing on a specific spot because someone said, “Look right there. Isn't that a bed bug egg?” The eggs are the size of a speck of black pepper or the thickness of a credit card. Bed bugs are frequently compared to the size of a grain of salt, but salt is only 1/10th the size of a speck of black pepper. I've also seen eggs compared to a grain of sugar, but sugar is even smaller than salt, so that is absolutely incorrect.

Then, after all that work trying to figure out the size of a bed bug egg, the beg bug hatches and continues to confuse us as it goes through five molting or skin-shedding stages, growing about 0.5mm with each molt.

So, once the bed bug hatches from its 1mm sized egg, we discover that the first nymphal stage is 1.5 mm or the thickness of a U.S. penny. That was an easy comparison. It gets harder.

The second stage of the bed bug nymph is 2 mm or the size of a small ant. Of course, that's pretty subjective because people react to insects in all sorts of strange manner. Some people see an ant crawling on their kitchen counter and, from the fuss they make, you would think they just saw a mountain lion streak by. So, let me think. Okay! I've got it. Two millimeters is the thickness of an average door key.

The third nymphal stage is 2.5 mm or about the same size as a flea. If you are a pet owner you probably are familiar with that size comparison. If you are not a pet owner, ask a dog owner you know if you can borrow a flea to examine. Only kidding about that one.

Insect pronotum (noted in red)

The fourth nymphal stage larva is 3 mm or the size of the diameter of the period of a typewriter. Oops! IBM stopped selling those babies a long time ago and the period comparison does not work on computer screens because everyone uses different type fonts and sizes. I cannot come up with something that always measures 3 millimeters in length so just know it's between 2.5mm and 3.5mm.

The fifth nymphal stage is 4.5 mm or the thickness of a stack of 14 business cards.

Lastly, the adult bed bug averages 5.5 mm or the thickness of the curly phone cord on your telephone.

So, the common misconception that bed bugs are not visible to the naked eye is wrong, wrong, wrong. Nor do they move quickly enough to avoid your attention. You can see them and you should most definitely be looking for them especially when you check into a hotel room or visit a strange, new place. Bed bugs are an ever-growing problem and they are showing up in more and more common places. Be on the lookout. Otherwise, you have a good chance of becoming a bed bug's next ride.

Click here to watch my short video on how to monitor for bed bugs.