Bed bugs: how do they see?

Although bed bugs love to feed on human blood, they do not have eyes that see like human beings. These parasitic creatures have what is called a compound eye structure. It is thought that they do not see in color, that they visualize in black and white.

The bed bug eye is made up of hundreds of eye lenses called facets that fit into a hexagonal structure. An easy way to imagine what this insect eye looks like is to think of a honeycomb in a conical shape and not a flat one. It is like a soccer ball, but on a smaller and more complex level. The individual facets consist of two lenses, one on the surface and one on the inside. Double lens bed bug eye frame allows you to see in 3-D. All these facets together form the eye of the parasite. These facets are connected to tubes that focus light onto a central structure called a rhabdom. The rhabdoma is sensitive to light and directs information through an optic nerve to the brain of insects.

Each individual facet in the bed bug eye sends a different image to your brain. When all these images are processed and put together, a mosaic is created. This three-dimensional mosaic is the way the bed bug can see its human host. It is not known if, as the bug moves, the image it sees is updated in its entirety or if each lens takes microseconds to update the visual information. If the vision of this parasitic insect is updated lens by lens, then you would see a constantly updating image. This view would be like looking through a kaleidoscope with 3D glasses on.

Bed bugs come out at night or in the dark to feed on their human hosts for a couple of reasons. One of the reasons is that at night, when you are in your bed sleeping, you will not feel that you are dragged and bitten. Another reason could be that these bloodsuckers have light-sensitive eyes that allow them to see better in the dark. These compound eyes can also pick up a heat signature from the human body. This is why most bed bug bites occur in the central part of your body mass. Its heat signature is warmer on your torso, legs, and arms than it is on your fingers and toes.

Humans can have constantly updating color vision, while bed bug compound eyes see in black and white. Their eyes don’t constantly update the whole image at once either, but they can see very well to do the job they are best at. That job is to find a human host to feed on their blood.