Bed bugs are indeed classified as parasites. A parasite is an organism that lives and feeds off of another organism, called the host. The parasite benefits at the expense of the host. Bed bugs need to feed on the blood of humans and other animals to survive, making them parasitic.
What makes something a parasite?
For an organism to be considered a parasite, it must meet several criteria:
- It must live on or in a host organism
- It derives its food from the host
- This relationship causes harm to the host
- It is physiologically dependent on its host, meaning it has evolved and adapted to this parasitic way of life
Parasites come in many forms, ranging from tiny viruses and bacteria to larger worms and arthropods. Some examples of common human parasites include:
- Tapeworms
- Roundworms
- Pinworms
- Scabies mites
- Lice
- Bed bugs
These organisms have all evolved specialized abilities to be able to live off of a host, evade the host’s immune responses, and propagate their life cycle. Many reproduce quickly and can be spread easily to new hosts.
Bed bug biology
Bed bugs are small, flat, oval-shaped insects that are reddish-brown in color. Adults grow to about 1/4 to 1/2 inch long. Newly hatched bed bugs are nearly colorless. After feeding on blood, they turn more red.
Bed bugs belong to the family Cimicidae and genus Cimex. There are over 90 species of bed bugs and the most common species associated with humans are Cimex lectularius and Cimex hemipterus.
Some key facts about bed bug biology and behavior:
- Bed bugs feed exclusively on blood.
- They are mainly active at night when hosts are sleeping.
- During the day, they hide in dark crevices and cracks near sleeping areas.
- They can survive for months between blood meals.
- They release anticoagulants into the blood to prevent it from clotting while they feed.
- They go through 5 immature nymph stages before reaching adulthood.
- Adult females lay up to 500 eggs in their lifetime.
This biology allows bed bugs to stealthily hide, feed, and reproduce effectively, making them successful external parasites of humans.
How bed bugs feed
Bed bugs use specialized mouthparts called piercing-sucking mouthparts to feed on blood. They have a proboscis shaped like a beak that contains two tubes – one sucks up blood, the other injects saliva and anticoagulants into the bite.
The feeding process includes the following steps:
- They seek out a sleeping host, often being drawn in by body heat, carbon dioxide, and odors.
- They pierce the skin using their sharp beak.
- They inject saliva which contains anesthetics to numb the bite area as well as anticoagulants to prevent blood clotting.
- They suck up blood through the other tube until they become engorged, which takes about 3-10 minutes.
- They withdraw the proboscis and return to their hiding spot.
This allows them to feed undetected on a host for an extended period of time. Adult bed bugs can survive over a year without feeding, but nymphs must feed about once a week to complete their development.
Effects of bed bugs on human hosts
Although bed bugs are not known to transmit diseases, their bites can cause a variety of negative effects including:
- Itching and skin irritation – The saliva and anesthetics injected by bed bugs causes red, swollen itchy spots on the skin in most people.
- Allergic reactions – More severe allergic responses to bites can occur in some cases, including blisters, hives, and severe itching.
- Anemia – In severe infestations with very repeated feeding, enough blood loss can cause anemia, especially in small children.
- Sleep loss – Itching from bites can lead to insomnia and sleep deprivation.
- Anxiety/stress – Dealing with an infestation causes significant stress, anxiety, and emotional turmoil for many people.
In rare cases, excessive scratching of itchy bite areas can cause secondary skin infections. The bites can also cause embarrassment for those affected.
Treatment and prevention
Eliminating bed bug infestations requires a multipronged approach including both non-chemical and chemical methods. Treatment steps usually include:
- Inspection to confirm and locate infestations
- Thorough cleaning and vacuuming to remove bugs and eggs
- Sealing cracks and crevices where bugs hide
- Applying residual insecticide sprays and dusts
- Using traps and monitors to detect ongoing infestation
- Follow up inspections and treatment as needed
Prevention is also key and revolves around avoiding introducing bed bugs into a home. Tips can include:
- Carefully inspecting secondhand furniture before bringing it home
- Checking hotel rooms for signs of bed bugs when traveling
- Placing luggage on racks away from beds and upholstery when in hotels
- Washing and drying clothes on high heat after returning from trips
- Sealing cracks and crevices in the home
Evolution of bed bug-human relationship
Bed bugs have evolved over millions of years specifically to feed on animals and humans. Some key points in the evolution of their relationship with humans include:
- Bed bugs first evolved around 50 million years ago, feeding on bats and eventually spreading to feed on other mammals and birds.
- They began feeding on humans once humans started living in caves alongside bats over 250,000 years ago.
- Bed bugs were widespread in human habitations until the mid-20th century when insecticide use sharply reduced their numbers.
- In the past 20 years, bed bug populations have surged back due to increased travel, bans on effective insecticides, and pesticide resistance.
Bed bugs have evolved specialized stealthy habits, reproduction, and physiology to exploit humans as predictable blood meal sources inside their homes and shelters. Their parasitic relationship with humans is long evolved and clearly demonstrates their classification as true parasites.
Conclusion
In summary, bed bugs meet all the criteria that define a parasitic organism:
- They live exclusively on their human hosts.
- They feed on human blood to survive and reproduce.
- They cause mild to severe harm to their hosts.
- They have specialized anatomy and behavior to exploit their hosts.
While bed bugs don’t spread disease, they can cause significant discomfort, stress, sleeplessness, and embarrassment due to their persistent and stealthy feeding on human blood. Their parasitic biology and close relationship with our species that has evolved over thousands of years clearly demonstrate that bed bugs are true parasites.