Life Cycle of Bed Bugs

To understand why bed bugs are so persistent and difficult to control, we need to have a grasp of their life cycle.

Bed bugs (Cimex lectularius) are small and wingless insects that primarily feed on blood. They are a public health issue as they bring about significant physiological and psychological problems to those whose homes and beds are infested. It is important therefore for affected parties to take the necessary steps to eliminate bed bugs. Before undertaking such steps, it is important to understand these bed bugs, their life cycle, and how they reproduce. Such information helps affected parties be more proactive and effective in their efforts to eliminate these pests.

All insects develop via metamorphosis. In this process, the appearance or form of the insect undergoes changes from egg and eventually to adult.  There are four types of metamorphosis, namely, no metamorphosis, gradual metamorphosis, incomplete metamorphosis, and complete metamorphosis. Bed bugs undergo gradual metamorphosis. This type of metamorphosis has three stages (egg, nymph, and adult). There is no pupal stage in gradual metamorphosis and the nymph already possesses the qualities of an adult.

The difference between the nymph and the adult is that the former is smaller and is not yet sexually mature. As soon as sexual maturity is reached, females have eggs which are ready to be fertilized by male sperm. Upon fertilization, the life of insects commences in fertilized eggs which are laid by the females.

Bed bugs begin their life as milky white and grain-like eggs. Females lay their eggs in clusters or one at a time and up to five eggs in a day, choosing crevices and cracks to release their eggs. When conditions are favorable, the survival of the eggs is high, and up to 97% hatch. Under similar favorable conditions, about 60% of the fertilized eggs hatch within six days of fertilization. The rest of the eggs fertilized at the same time hatch within 9 days. When temperatures are lower, the eggs usually hatch sooner. Where ideal conditions for hatching and reproduction are present, bed bugs can double their population in a matter of 16 days. As eggs, they measure about a millimeter long. Within two weeks from the time they are laid, they hatch and start to feed. The emerging bed bugs are known as nymphs.

Nymphs are young bed bugs that have to undergo five nymphal states to reach the adult state. In other words, they have to molt five times before they become fully developed adults. These nymphs are not sexually mature and are therefore unable to produce eggs. The younger nymphs are lighter in color, yellowish-white, and the older nymphs are more reddish brown, similar to the color of adult bed bugs.

Nymph development is largely based on numerous factors, including ambient temperature and access to a host. An ideal room temperature of (>70^oF) would mean that the nymphs would reach the next instar in the five-day period following their feeding. For instars that have just molted and have been able to feed within 24 hours, their next instar period would once again be in the next 5-8 days.

Where temperatures are lower, the molting or nymph development would take two to three days longer to reach. Without any blood hosts, however, the nymph will simply stay in its current instar stage.

Nymphs that are in their first instar stage have lower survival rates. They are usually very tiny and have to travel longer distances to reach blood hosts. Where these new instars are unable to locate hosts, they usually dehydrate and die. The survival rate of bed bugs however is still particularly high especially where conditions are favorable. Bed bugs are considered adults after completing all five nymphal stages.

In order to sustain the life of adult bed bugs, they have to undergo weekly feedings. Adult bed bugs which were studied in a laboratory, placed under ideal conditions for survival, were able to live for about 99 to 300 days. There is no study yet observing their survival in ideal conditions in homes or apartments. Experts believe that bed bugs in non-laboratory settings would survive for several months even where conditions are not ideal. Their rate of survival however would be challenged by various factors including changes in temperature, physical factors (being stepped on and crushed), and the use of insecticides.

Starvation is still considered the greatest threat to bed bug survival. While previous studies in Europe indicated that bed bugs can last for more than a year without feeding, more current studies in the US have debunked European results. Starved bed bugs that were studied in the US died within 70 days. These bugs died due to dehydration, not starvation. The lack of hydration is therefore also a major threat to bed bugs.

After feeding, bed bugs, especially males, are eager to mate. Their method of mating is known as traumatic insemination. The insemination is traumatic because the male bed bug usually stabs the female’s body wall with his reproductive organ. The stabbing of the female by the male’s reproductive organ often leaves a wound and later a scar on the female’s body. The female’s specialized organ known as the Organ of Berlese is to her right and to reach it, her body wall needs to be pierced.

The male then releases his sperm into the female and in the hours following, the sperm moves towards the ovaries where her eggs are then fertilized. The female bed bug’s body has to heal from her wound and to facilitate this, the female usually leaves the grouping of bed bugs. In some cases, a female bed bug can be stabbed and inseminated numerous times by males.

Studies reveal that females who are stabbed and mated with only once are able to produce 25% more eggs as compared to females who are stabbed numerous times. This would mean however that even one single female which has mated can actually cause an infestation. For as long as she feeds, she can produce numerous fertilized eggs and such eggs can mature into adult bed bugs. Female bed bugs are also able to produce up to seven eggs a day for 10 days with only one blood feed. This converts to about 5-20 eggs produced by a female in only one feeding.

Regular access to blood meals for female bed bugs means that they can keep producing eggs. More frequent blood feeding would translate to more eggs. The female bed bug, which can feed on a weekly basis, for instance, would be able to produce more eggs as compared to the bug feeding on a monthly basis.

At each stage of the bed bug’s life cycle, these insects have to feed on blood. Like other insects, the skeleton of bed bugs is outside their body, and in order to achieve growth, their external skeleton (exoskeleton) has to be shed. Shedding the exoskeleton is known as molting, and to ensure successful molting, the bed bug has to feed on blood. With five successful molting incidents, the bed bug grows until it eventually reaches the adult stage.

Female bed bugs, compared to male bugs, need to feed more because they require blood to develop their eggs. The five stages of the bed bug larva last about a month when conditions are conducive for development and blood is available for consumption. The bed bug larvae are able to survive for months without feeding on blood. They simply do not molt or progress to the next stage of their cycle. Adult bed bugs are also able to survive for days without feeding. The aspect of their development which is affected by the lack of food is their egg development. Until they feed, these adult bed bugs do not develop eggs.

To survive during the day, bed bugs hide in cracks, crevices, and similar other spaces. They usually stay undisturbed and unseen in these spaces. At night, they become active and from midnight to 5 am they look for blood hosts. As fast crawlers, they can travel far, often attracted to the carbon dioxide and body heat of human hosts. These bugs however are only able to detect carbon dioxide and heat for short distances. Nevertheless, as fast movers, they can effectively wander around to detect cues from blood hosts. When they are not feeding, bed bugs usually congregate near or at the bed of their hosts, on the mattress itself, and on box springs.

Where there are already infestations, bed bugs usually distance themselves yards away from more crowded areas. As soon as their host is within distance, they travel quickly to gain access to their host. To feed, they penetrate the skin of their host with their piercing and sucking mouth. They then secure themselves in a capillary space under the host’s skin and proceed to access blood. To find the perfect spot to feed, bed bugs usually penetrate the skin of the host numerous times. As a result, the host can have numerous bites from the same bug. Feeding time can take about 5-10 minutes.

When full, the bug leaves the host to once again settle into cracks and crevices. The preferred spaces at this point would be those where other bed bugs have aggregated. Bed bugs feed for about 3-7 days and after feeding, proceed to digest and excrete their meal. This would mean that bed bugs are not always feeding, sometimes they are also in digesting stages.

In understanding bed bugs, their life cycle including their feeding and mating behavior, coming up with a plan to exterminate them once and for all becomes easier. These are some of the things that can be done to eliminate bed bugs:

• Physically eliminating bed bugs as soon as they are seen in one’s home.
• Checking the home regularly, especially the beds, furniture, closets, carpet, blankets, and any crack or crevice for bed bugs
• Seal pillows and mattresses with zippered covers
• Eliminate clutter in the home to ensure that these bugs are immediately seen and detected, and that they have no available spaces to hide during the day.
• Cracks and crevices in the home should be sealed.
• Contact BBE Bed Bug Exterminator’s highly trained consultants and exterminators for a proven-effective heat treatment consultation.