A Guide to Bed Bug Size and the Bed Bug Life Cycle
Knowing how big bed bugs are at different stages in their life cycle can help you identify an infestation.

In recent years there has been a tremendous increase in the number of bed bug infestations reported. Research suggests that this new influx of bed bugs is in large part due to the increase of international travel and immigration. Many countries around the globe are reporting higher levels of bed bug infestation. It would appear that these insects have hitched a ride back with visitors and citizens of the United States where they have found comfort in hotels, apartments, dormitories and yes, even your home. This is not by the way, an indication of being unclean; bed bugs are equal opportunity pests.

Okay, we have determined that the bed bugs are here and that we need to deal with them. As with any foe, the first step is to educate ourselves about our enemy. The more you know about bed bugs, the better the chance of being able to take back your home. As a starting point, here is the bed bug life cycle.

The Bed Bug Life Cycle

The Bed Bug Egg

The bed bug egg is generally laid in a sheltered location such as a mattress, thin crevices in box springs and under base boards. Typically the adult female bed bug will lay about 5 eggs at a time daily through her life time.

The First Nymphal Instar Phase

This nymph stage is the earliest in the bed bug life cycle. At this point in its development the bed bug size is quite small, the hatchling itself is only about the size of a poppy seed.Measuring in at 1.5mm. In this early bed bug lifecycle their color will range from a white or light tan color to that of a brown or burnt orange. Before the bed bug can progress to the next stage it most feed and molt. Before the molt the bed bug is referred to an instar.

The Second Nymphal Instar Phase

After its first feeding and engorgement, the bed bug size begins its progression towards adulthood. In the second nymphal instar stage the bed bug size is now about 2 mm long.

The Third Nymphal Instar Phase

As the bed bug enters its third stage of development it continues to feed in order to molt, The bed bug size in the third instar state is 2.5 mm long.

The Fourth Nymphal Instar Phase

Now the bed bug has reached its next to last stage. Once it feeds and molts it will enter a rapidly growing period. At this point however, the bed bug size is now 3 mm long.

The Fifth Nymphal Instar Phase

By this time it has been about 6 to 8 weeks since the bed bug emerged. It is now in its final nymphal stage. The bed bug size has jumped to 4.5mm a huge growth for such a tiny insect. With its next molt it will become an adult.

Adult Bed Bugs

Once passed through the five nymph stages, the next step in the bed bug life cycle is the adult stage. Physically, the adult bed bug is flat in nature from bottom to top and is oval shaped. Their color is a reddish brown. The adult bed bug size is about 1/4 of an inch long and oval shaped. Their eating habits require about 5-10 minutes of feeding from the host.

The bed bug life cycle can only continue as long as they have a host from which they feed. The sooner the bed bugs are detected, the sooner you can take action to eliminate them.