In order to properly identify a bed bug, it helps to know exactly what to look for. Characteristics such as color, shape and size can help you differentiate bed bugs from other insects.

bed bug size

Bed bugs have two antennae, six legs and oval-shaped bodies. They’re relatively flat and small, with bed bug sizes ranging from 1 mm to 7 mm, depending on their age and life cycle stage. Coloration also varies with age and how recently they’ve blood fed. While immature bed bugs - also referred to as nymphs - are semi-translucent, adults tend to be reddish-brown before a blood meal and bright red immediately after blood feeding. Check out the bed bugs pictures shown here to get an idea of their actual size and to familiarize yourself with their characteristics.

Bed Bug Pictures: Actual Size

The first thing most people do when trying to identify a potential bed bug is to examine bed bug pictures. The actual size of bed bugs can vary, depending on life stage and age. To help understand bed bugs and their life cycle, here’s a general bed bug size comparison of each stage:

  • Eggs are tiny, about the size of a pin head (1 mm)
  • 1st stage nymph (1.5 mm)
  • 2nd stage nymph (2 mm)
  • 3rd stage nymph (2.5 mm)
  • 4th stage nymph (3 mm), about the size of a sesame seed
  • 5th stage nymph (4.5 mm)
  • Adult bed bugs (5-7 mm or 3/16-1/4 inch), about the size of an apple seed

The life cycle of a bed bug includes multiple nymphal stages, with the insects blood feeding between each nymphal stage. Bed bugs typically mature in two to six weeks (depending on environmental temperature and availability of blood meal hosts) and adults can survive for six months to a year without blood, however the females must have a blood meal in order to reproduce. Ideal temperatures for bed bug propagation are above 70°F. Considering a single female can lay between 200 and 500 eggs in a lifetime (10-50 eggs laid at a time) even a single bed bug sighting should be taken seriously to help curtail the reproductive cycle of these insects. Pest control professionals should be consulted as early as possible to identify and control a potential infestation.

Bed Bug Size Comparison and Lookalikes

Bed bugs can easily be mistaken for some other types of insects, such as bat bugs, swallow bugs, lice, carpet beetles and fleas. Whether you’re interested in familiarizing yourself with bed bug characteristics before traveling or trying to determine whether or not you have an issue in your home or other areas, it’s important to understand some of their basic characteristics.

In general, adult bed bugs are:

  • About the size of an apple seed (5-7 mm or 3/16-1/4 inch long)
  • Flat, oval-shaped and reddish-brown (if not blood fed recently)
  • Balloon-like and bright red (if blood fed recently)
  • Produce a foul, somewhat musty odor
  • Not known to jump or fly, but walk instead
  • Unlikely to live on human hosts, but come out from hiding spots to blood feed

It can be difficult for untrained individuals to correctly identify bed bugs based solely on the aforementioned characteristics like size and/or color, but having this information, in addition to bed bug images, can help make the process a bit it easier. If you’re unsure whether or not an insect you’ve seen is a bed bug or are concerned that you may have an infestation, an on-site assessment by a professional pest control technician is recommended. Consider contacting Terminix® today for a FREE inspection, and find out how our customized treatments can help eliminate bed bugs.