Sunday, April 28, 2013

Meet the Crimson Rambler

When I was a child, my many other mothers...used to say, "Good night.  Sleep tight. Don't let the bed bugs bite!".  Good advice for a child not sure what bed bugs really were...otherwise I'd probably have had nightmares!  I spent most of my young life thinking bed bugs were mythical because of that phrase.  As I got older, I discovered that they were very real creatures that actually do bite people as they sleep.  As you can imagine, I was filled with fear and panic when I first learned about how pesky these little buggers can be.  As I've grown into the young parasitologist that I am, these pests have moved from something I fear to something I find fascinating.  Like most other parasites, these guys have very interesting lives and guess what...they aren't terribly dangerous to tell the truth.  The worst they can do is be an annoyance and an extremely difficult one to rid yourself of at that.  So, today we look at the strange lives of these odd insects that have had aliases such as the "wall louse", "heavy dragon", "chinche bug", "redcoat", and my personal favorite, "crimson rambler".  

These animals belong to the largest of all the animal phyla: Phylum Arthropoda.  Within this phylum they exist as members of class Insecta.  Something tells me you can guess what other types of creatures make up this class.  They belong to order Hemiptera, meaning "half-wing", which refers to the partially membranous wings of most member of this order.  Interestingly enough, not all members of this order have wings (as we see with bed bugs).  However, members of this order do all possess piercing-sucking mouthparts often called the proboscis. This is used for penetrating tissues..both animal and plant in nature. They further belong to family Cimicidae.  Members of this family are all wingless blood-feeders that seek out birds, bats, and humans. There are 22 genera within this family; twelve feed on bats, two on humans, and the rest on birds...typically birds that live in caves or along cliffs.  The three species that feed on humans are colloquially called "bed bugs" due to their nocturnal feeding habits.  These three are Cimex lectularius, Cimex hemipterus, and Leptocimex boueti. The first is the most commonly found species globally, but prefers temperate climates, while the second prefers more tropical areas.  The last is found only in West Africa.

Bed Bug Bodies
SEM of a bed bug.  The piercing mouthparts have
been artificially colored with purple and red.
As mentioned previously, these little bugs are wingless...actually, if you want to be technical, they have vestigial (reduced to the point of being useless) wings. As adults, they are small reddish-brown ovals reaching as big as 5mm x 3mm in size.  Newly hatched nymphs are transparent, but become progressively darker as they go through successive molts.  These insects use chemical signals to communicate with one another about nesting, feeding, and reproducing.

Coming Out of the Woodwork...Err...Cave-work?!
These insects can proliferate quickly and be extremely difficult to eradicate once they have an established home.  But where did they originally come from?  Though no one can say for sure when or where bed bugs originated, we do know that the three species that feed on humans are also known to feed on bats.  It is likely that humans picked up these parasites from living in caves alongside infested bat colonies.  C. lectularius has also been known to feed on rodents, which may have helped to spread these insects into human dwellings outside of caves.

There is a long and fascinating history associated with these little bugs, but I'll save that for a future post. Today, we are experiencing a time of resurgence in bed bug populations.  As more people take over the planet, we build more places to house more people in fewer areas.  This space-saving comes with a price. Not only are apartments, dorms, and condos more prone to infestations with cockroaches and ants, now we are seeing more and more cases of bed bug infestations as well.  As you probably would have guessed, they are a bigger problem in places with larger populations.

The Feeding: Adventures of the Crimson Rambler
After closing your eyes and drifting off to dreamland, these little creatures make their way out of mattresses, dressers, pillows, and cracks or crevices in the walls near your bed. They find their way to you by detecting the carbon dioxide you exhale with every breath, by feeling the warmth of your body heat as they get closer, and by using a variety of navigation chemicals.

After discovering your exposed skin, the creatures pierce you with their tiny little beaks.  This blood derrick finally strikes paydirt when it enters into a blood vessel.  From here, the pressure within the vessel itself forces this iron-rich liquid into the body of this miniscule beast. Their bites are not painful and often go unnoticed in the beginning. The wounds left behind eventually become small itchy welts around your neck, arms, and jaw. The bug draws on the fresh blood for the next 5-10 minutes before dropping off and crawling back into the home from which they emerged. This is a ritual that occurs every 5-10 days.

Despite the fact that these creatures tend to feed once or twice a week, they can actually go for about 5 months without feeding under typical conditions.  Under ideal conditions (for them) they can live for up to a year.  Speaking of time, here's a fun fact: These insects digest their blood meals slowly and human DNA can be recovered from bed bugs up to 90 days post feeding!  This gives them a unique place in forensic entomology for determining whether or not a person was in a place where the bed bugs were found!
Male (behind) traumatically inseminating a female.
And the Most Traumatizing Mating Ritual Goes To...
One of the things that I've always found most fascinating about bed bugs is their means of reproduction.  These animals mate when a male finds a female, grabs her from behind, and literally stabs her in the abdomen with his hypodermic genitalia.  That's right hypodermic genitals.  After the stabbing, he ejaculates into her body and the sperm swim around in her hemolymph until they reach sperm storage structures.  Eventually, the sperm are released and move to the ovaries where fertilization occurs.  This process is appropriately called traumatic insemination.

Human Health Issues
Bed bug welts.
Despite being exclusive blood feeders, and being known to become infected with over 28 human pathogens, these animals have never been documented to have transmitted any diseases to humans.  The worst that these bugs can do is cause skin irritation that may be mild or could cause blisters in sensitive individuals. The biggest problem humans experience when living with bed bugs is the psychological effect associated with living in an infested home.  Much fear and disgust surrounds these organisms, and it is easy to have such feelings when faced with an infestation. 

These bugs are often associated with sub-par living spaces in our minds, but the truth is that a home can be a very nice home and still get an infestation.  They can be brought into a home through clothing, luggage, furniture, etc. from an infested home.  They can also come from wild animals or pets that have been exposed to nesting sites.

Detection and Management
Bed bugs are not always easy to detect because they are nocturnal feeders, usually feeding in the wee hours of the morning.  If you haven't had any reactions to the bites, you can still detect bed bugs by finding their fecal spots, blood smears on your bedding, or empty exoskeletons left behind as the insects molt.

A bed bug harborage.
Sometimes you can find a single bed bug, but they are more often found congregated at nesting sites.  These clusters of bed bugs, young and old, are often known as "harborages" and are the end of the chemical trail after feeding for most of these insects.  Harborages can exist in bedding, luggage, furniture...even electrical sockets and laptops.

Some people employ the help of specially trained bed bug detection dogs to help them find harborages.  Apparently, these dogs are very good at their jobs.  Under controlled lab conditions, these dogs are 97.5% accurate.  Of course, we expect that rate to be lower under real-world conditions, but that's still pretty impressive! Bed bugs are said to have a smell that some describe as rotting raspberries.  Trained dogs can typically pick up on the origins of these smells within minutes, which pest control specialists usually need about an hour.
A New York bed bug detection dog.

Bed bugs die if exposed to 115°F heat for 7 minutes or more.  Heat along with pesticides like malathion are the best course of action for managing bed bug infestations.  These animals can also be killed by freezing temperatures, but this takes several days rather than a matter of minutes. It is also recommended to vacuum areas, heat treat bedding and mattresses, and above all else to call in professionals to help with eradication efforts.  In extreme cases, you may have to dispose of a heavily infested mattress or couch.

There was an interesting paper that came out recently talking about a traditional method of bed bug control that involved the use of plant leaves scattered around the bed as traps.  Apparently this method actually works to some degree and scientists are working to develop artificial traps that have the same design as the hairs on these bed bug-snaring leaves.  More about that paper in a future post.

Bed bugs and their eggs
inside an infested dresser drawer.
To prevent bites, try to minimize the amount of skin you leave exposed while you sleep and think about infesting in a pesticide-impregnated mosquito net until you know you have gotten rid of these insects.  To prevent bringing these guys home be careful of secondhand items and sketchy hotels. Keep your luggage off the floor when possible in hotels, even non-sketchy ones may be infested. Bed bugs don't need a dirty place to live...they just need a place with hosts and lots of hiding places. Also, be sure to thoroughly look at your personal items after a trip...especially if you were in close proximity with birds or bats...and be sure to wash your trip clothing with hot water and dry them in a dryer for at least 20 minutes at a medium-high heat.

If you do develop skin problems from bites, you can treat them using a hydrocortisone cream or an oral antihistamine like Benedryl.  The bites usually heal within a few weeks.

Moral of the Story
If you get bed bugs, be sad that you have something hard to get rid of, but happy that you have something that can't transmit any sort of deadly disease! (Always a silver lining!) These creatures are fascinating even though they cause a lot of human annoyance and can be costly to eradicate from your home. Be in awe of the crimson ramblers...just hope you never have to deal with them up-close and personal! :p

1 comment:

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