What is metamorphosis?
The life cycle of an insect describes the development of an insect from the egg stage to adult. The process is referred to as metamorphosis. Metamorphosis is the process that the insects undergo to change from egg to adult. During complete metamorphosis, the insect egg is laid and when the egg hatches, a larva emerges that has little resemblance to adults. After feeding for a period of time, the larva changes to a new appearance. This stage in development is called the pupal stage. During the pupal stage, the insect will rest for some time before completing the final stage in development. When the pupa develops into an adult and emerges, the final stage of metamorphosis is achieved.
Bed bugs evolve in a process called simple metamorphosis. This means that the juveniles have the appearance of adults and there is no resting or pupal stage. So the bed bug life cycle goes from egg to nymph, progressing through five nymphal stages, to adult, which then lays eggs and the process starts again.
Bed bug eggs are small, about 1/32 of an inch long.
Where Do They Lay Eggs?
The eggs are “cemented” in place in hidden places such as folds of cushions in chairs, behind head boards of beds, in screw holes of furniture, and in box springs. Any hidden place seems to be a target for females to lay their eggs. Bed bug eggs hatch quickly under temperatures and humidities agreeable to humans.
From egg to egg, the life cycle of the bed bug is four to five weeks. The eggs have a cap which is opened by the emerging nymph. As the nymph exits the egg, the egg case will appear wrinkled. The cap remains attached to the egg after the nymph emerges. Empty eggs remain with viable eggs and do not come loose from the surface where it is attached.
Time of the Cycle
Eggs take about a week to hatch. Bed bugs are most active when their living space is just under body temperature, so a room temperature that is about 80° Fahrenheit is hospitable. After hatching, the nymphal stages begin and if there is adequate food, temperature, and humidity of about 75%, bed bugs will thrive. They can produce several generations per year, so egg to egg can be timed in just a few months.
How Many Eggs?
Females may lay between 200 and 500 eggs in their lifetime which may last for two years. If you calculate the number of eggs laid by a female and that from egg to adult can be four to five weeks, it becomes apparent that a population may number thousands in a short period.
If vacuuming is used to rid the area of bed bugs, eggs typically remain and will hatch out after the live insects are removed. Eggs left in place are not known to carry any disease. There is no known insect predator of bed bug eggs. Used furniture is a particular culprit in the spread of bed bugs as even if the live insects are removed, eggs can remain. Eggs can be destroyed by heat or certain control products. Clothing which has eggs attached can be put in a dryer for fifteen minutes to destroy the eggs.
After hatching from eggs, bed bugs go through several stages of growth as juveniles, called nymphs.
There are five nymphal stages before a bed bug becomes a fully grown adult. Each stage requires molting or shedding of the shell to enter the next stage. Each stage is called an instar so that the stages can be termed first instar nymph, second instar nymph, etc.
Nymphs feed on blood
After hatching from the egg which is approximately 1/32” long, the first instar nymph is nearly as long as the egg and almost clear in color so that they are nearly invisible due to their size and color. In order to move to the next instar, the nymph must feed on blood, preferably human blood. Each nymph may feed multiple times before they move to the next instar stage. Usually, bed bugs will feed from three to ten minutes to repletion. They can also feed a few seconds and move to feed at another location on the host.
Later stages of development
As the nymphs reach later stages, they can be seen. Early instar nymphs will be the color of blood after feeding since they have no color of their own. Later instars may appear to be a brownish color even before feeding. Late stage instars resemble adult bed bugs. It is important to note that nymphs do in fact feed on blood and they are difficult to find in an infestation. It is also important to understand that bed bugs feed on nothing other than blood so infestations are possible anywhere humans are from homes to hotels to libraries to movie theaters.
How Long Do Bed Bugs Live?
There is a great debate as to how long bed bugs can live.
While it is rare in normal populations, there are documented cases where bed bugs have been dormant and waiting for a host for over a year. Moreover, there have been rare cases where bed bugs have survived two years without feeding.
Generally, bed bugs will survive longer if they have slowed their metabolism due to colder temperatures. Bed bugs which have been subjected to temperatures near 50 degrees Fahrenheit can survive for well over a year while bed bugs with accelerated metabolism due to temperatures approaching human body temperature might not survive as long.
In captivity, in the lab, modern anecdotal reports show that bed bugs with adequate food at ambient room temperature (72 degrees Fahrenheit) will typically survive for just a few months. It appears that bed bugs are similar to other animals even including humans: survival depends on genetics, exposure, food sources, and the environment.
Without a doubt, bed bugs can survive over a year. They can also survive that time without a blood meal. However, the nymphs are more sensitive to lack of food than adults. Newly hatched nymphs need a blood meal within a few days and first and second instar nymphs are most sensitive to lack of food.
Virtually any report of bed bugs surviving over a year can be considered true. Also, starved adults surviving more than a year can be considered possible.