The moon hangs low in the sky, its light filtering ever so slightly through your bedroom window. You lie entangled in your sheets as you dream of adventure in far off places. But what’s that? A mysterious creature huddles in the dark corners of your room watching you sleep. It creeps forward, but you’re blissfully unaware in a deep slumber. Leaning in, this treacherous monster bites down into your skin, sucking away your blood, your life force. Oh the horror!
Despite being on a bed bug blog, I’m assuming more of you were picturing an Alexander Skarsgård type than an insect. Which, frankly, I can’t blame you. It’s much more appealing to think of an attractive, brooding, bad boy type lurking in the shadows than a 6-legged bug tucked in the seam of the mattress. (I’ve been looking at pictures from the show True Blood all morning just to confirm this. Purely, strictly research, I promise.) But why is this? Granted, one is a mythological creature found only in movies, TV and nightmare, but both consume blood. When you think about it, the drop or so a bed bug needs to survive is a lot less invasive and offensive than the potentially lethal amount a vampire would need to consume. Yet vampires remain more attractive. There’s a lot of sociological research out there about why vampires have become so sexy; ranging everywhere from being misunderstood outsiders to reflections on human gender and sexualilty identities. Bed bugs, on the other hand, make us consider our interactions with other humans, both in our perpetual interaction with them and our fear of what they think of us. Vampires, though, have only had this prowess since Bram Stoker wrote Dracula in 1897. Prior to that they were feared just as much as we fear real blood suckers- of which there are many.
Hematophagy is the practice of feeding on blood. Hematophagy isn’t limited to bed bugs or mythological creatures. This type of feeding, also known as phlebotomy, has evolved separately over several different species including arthropods, worms, nematodes, leeches, and even some vertebrates. Blood is a good source of proteins, carbohydrates in the form of glucose, lipids and minerals and is easier to get for the predator than attempting to hunt and kill the entire prey. Hematophagy can be either obligatory, where the animal feeds only on blood, or optional, where it’s a supplement to their diet but not the only thing they eat. Sanguivores (animals that eat blood), have adapted several mechanisms to aid them in getting blood. One of the most important adaptations are the specialized mouthparts that allow them access to the blood, usually either needle-like teeth or a single hollow tube called a proboscis (which is what bed bugs have). In addition, sanguivores often have physical or chemical methods for detecting body heat, light, sweat, or CO2 to aid in finding a food source. They are usually nocturnal to avoid detection by those they are trying to feast upon.
What does this mean for humans? Since human blood is about 95% water with the remaining being proteins, sugars, minerals and a few other small molecules, it’s really only good sustenance for arthropods. This is a perk for us, since they only consume a slight amount of blood. Depending on the type of insect, an average meal can range from 0.0055ml to 0.8ml. Bed bugs are actually on the 0.0055 side of that spectrum. Given that the human body has roughly 5 liters of blood in it, a bed bug consumes about one millionth of the blood in your body when it eats. To put that in perspective, if you were to donate a pint of blood to the Red Cross, and the bag was high-jacked by a rogue group of bed bugs, that pint could feed 86,032 bed bugs. (Think about that next time you’re nibbling those free cookies after donating.)
If the sanguivores that are feeding on humans are taking such a small portion of blood, why are we so bothered by it? The bites themselves can often be itchy or painful. Most hematophagous animals have specialized saliva with anticoagulants and anesthetics to avoid detection while feeding. People have varying levels of allergies to this saliva, which is why some people never react to bug bites or others (like me) itch to the point of near insanity. Often hematophagous species can transfer infectious diseases like Lyme disease, rabies, the plague, malaria, West Nile, typhus and many others. It’s important to note that bed bugs are not known to transfer any diseases. When bed bugs insert their proboscis into the host’s skin there’s one channel for injecting their saliva and another for removing blood. The blood and saliva never mix and therefore no transference of disease.
Just because we’re squeamish about it, doesn’t mean humans don’t use hematophagy for their benefit. One of the most common is the use of leeches for blood-letting in the medical arena. Sure, it sounds like such an antiquated thing stick some leeches onto someone to “balance their humors”, but modern medicine still does use them for hirudin (the anticoagulant they make) and to relieve the pressure of pooling blood in certain surgeries. Humans aren’t excluded from being optional sanguivores either. In some cases, it’s considered ritualistic or spiritual, like drinking the blood of the first enemy killed in battle or symbolically drinking the blood of Christ in Christian churches. In other cases, there are common foods made out of blood like blood sausage eaten around the world or the combination of cow’s blood and milk that the Maasai people of Tanzania drink.
Okay, so what’s the point here, other than grossing you out? Bed bugs give us the willies. I have friends who can’t read this blog because the mere thought of bed bugs makes them all itchy. But these bloodsuckers aren’t alone. Although despite the fact that they consume very little blood and aren’t known to transmit any diseases, we still fear them with the same revere as Dracula. But hematophagy is just a way for several species to survive and get the basic nutrients they need. So the next time you see a bed bug scuttling towards you remember that he’s just trying to get by like the rest of us, but then remember that you like that 1/1,000,000 of blood he’s after just where it is and smash him with the heel of your shoe with the fiery vengeance of Buffy the Vampire Slayer.
Brittany is a licensed pest management professional.
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