Bed bugs are small, parasitic insects that feed on human blood. They are about the size and shape of an apple seed and are usually light brown to dark reddish-brown in color. When bed bugs feed, their bites often leave small red welts on the skin that may itch. However, one thing many people wonder about bed bugs is what color their blood is after they have fed.
Quick answer: The blood of bed bugs is clear/yellowish until it is digested
freshly-fed bed bugs have blood in their bodies that still resembles human blood – it is red and opaque. However, bed bugs have a fast digestion process that breaks down the blood quickly. Within just an hour after feeding, the blood turns from red to a clear or yellowish color as it is digested by the bed bug.
So in summary:
- Right after feeding, bed bug blood is red like human blood
- Within an hour, it turns yellowish or clear as digestion occurs
- Old or dried bed bug bloodstains may appear brownish-black
What does bed bug blood look like during the digestion process?
Here is a more detailed look at how the color of a bed bug’s blood changes during digestion:
- Bright red: Immediately after feeding, the bed bug’s blood will be a bright red color, similar to how human blood appears. It has not yet started digesting the blood.
- Dark red: Within 30-60 minutes after feeding, the blood turns a darker, more opaque shade of red as digestion begins.
- Yellowish to clear: 1-3 hours after feeding, the blood has been processed and broken down. It will become a clear or yellowish liquid as the red blood cells are digested.
- Clear or gone: By the time a bedbug is hungry to feed again (3-7 days), the blood from the previous meal has been fully digested and utilized. The abdomen will appear clear.
So in the first few hours after feeding, you can clearly observe the changes in blood color from red to yellowish inside the bed bug’s body. After a couple days there will be little or no sign of the blood left.
Why does the blood change color so quickly?
Bed bugs have a very efficient digestive system that allows them to quickly break down blood proteins and utilize the nutrients. Here are some key reasons their blood changes color so rapidly after feeding:
- Fast acting enzymes start breaking down blood cells immediately.
- The midgut expands to handle the large blood volume, keeping it in contact with digestive enzymes.
- Body heat helps accelerate the enzymatic digestion.
- The blood does not clot due to the bed bug’s anticoagulants.
- Red blood cells are quickly lysed and nutrients absorbed into the body.
In addition, bed bugs do not have any way to store excess blood or nutrients for later use. They must immediately digest each blood meal. This accounts for why the blood color soon disappears after feeding.
What color are bed bug bloodstains?
When bed bugs feed on humans, they often leave behind visible bloodstains on sheets, mattresses, furniture, and other surfaces. These stains provide evidence of bed bugs even after the bugs themselves have left or been eradicated. But what color are these dried bloodstains?
- Fresh stains will be bright or dark red.
- After 1-2 days, stains turn brown or rust colored as the blood oxidizes.
- Old stains appear as black or dark brown spots.
- The stains do not easily wash out and can persist for several weeks.
Here is a table summarizing the color changes:
| Time Since Feeding | Color of Bloodstain |
|---|---|
| Less than 1 day | Bright to dark red |
| 1-2 days | Rusty brown |
| 1 week or more | Blackish-brown |
As you can see, the bloodstains change from red to brownish-black over time. Knowing these color patterns can help identify bed bug infestations.
Do different bed bug species have different blood colors?
There are several species of bed bugs that feed on humans, with the most common being Cimex lectularius. Others include the tropical bed bug Cimex hemipterus and the bat parasite Cimex pilosellus.
All bed bug species have the same rapid digestive process and blood that turns from red to clear after feeding. The only minor difference may be slightly varied blood shades due to varied chemical makeups. Here are some minor color differences:
- Cimex lectularius: Bright red to yellowish
- Cimex hemipterus: Slightly more orange tinted blood
- Cimex pilosellus: Darker, more purple-red blood
However, these are only subtle variations. The process of the blood changing from red to clear within hours is essentially the same across all species.
Can bed bugs carry infections through blood?
A common concern is whether bed bugs can spread diseases through their bites. However, there is very little scientific evidence showing bed bugs transmitting infections between humans.
Some key reasons bed bugs are unlikely to cause infections:
- The bugs do not live long term inside human hosts.
- They have short mouthparts that do not reach deep blood vessels.
- The bite itself does not transfer much blood.
- They carry little to no detectable microbes or pathogens.
- Their digestive system kills most microorganisms from blood meals.
While not impossible, the chances of catching a disease from bed bug bites is extremely low. The red color of freshly fed bugs may alarm some people, but it does not mean they are harboring or transmitting human infections.
Do bed bugs urinate red?
Since bed bugs consume large amounts of blood, some wonder if their urine or excrement could also be red. However, bed bug urine and feces do not contain blood.
Reasons the excrement remains black or brown in color include:
- Feces consists of digested blood and other waste products.
- The red blood cells have been lysed and nutrients absorbed.
- Urine consists of excess water and metabolites, not blood.
- The yellowish liquid portion of blood is excreted.
- Any red pigments from blood have been processed and altered.
So while bed bug feces or urine stains may indicate signs of an infestation, they will remain dark brown or black. The bugs do not excrete visible amounts of red blood.
Do all bed bugs feed on humans?
While the most discussed bed bugs feed on human blood, there are also some bat and bird specialist bed bugs that do not regularly bite humans. The three main categories are:
- Human specialist: Feed exclusively on humans. Includes Cimex lectularius.
- Bat specialist: Feed on bats and their blood. Includes Cimex pipistrelli.
- Bird specialist: Feed on avian hosts. Includes Cimex adjunctus.
The different species have adapted to chemical cues, habitats, and behaviors of their hosts. However, in the absence of bats or birds, some may opportunistically bite humans if severely hungry. But human blood meals would still turn their blood red until digested.
Do bed bugs produce red spit or vomit?
Some small insects like biting midges regurgitate red saliva after feeding on hosts. However, bed bugs do not regurgitate blood back up after feeding. Any “spitting” behaviors are limited to defensive secretions:
- Fecal spots: Small droplets of excrement may be expelled when alarmed or crushed.
- Defensive odor: Smells unpleasant but is not blood. Used to deter predators.
- Traumatic insemination: Injects sperm into mates, not humans.
So while bed bugs produce various secretions, visible red vomit or spit from blood meals does not occur with these insects.
Do any other insect pests feed on blood?
While bed bugs are one of the most notorious blood-feeding pests, there are various other insects that also bite humans and animals to consume blood, such as:
- Mosquitoes
- Fleas
- Kissing bugs
- Black flies
- Sand flies
- Leeches
- Lice
- Mites
Any insect that feeds on blood will have red blood meals digestion and show color changes similar to bed bugs. However, other pests may spit or excrete blood components when disturbed. The bed bug is unique in fully digesting blood so that it leaves no visible red traces.
Should I be concerned about crush stains from bed bugs?
When you notice a spreading red stain or spot where a well-fed bed bug was crushed, it can admittedly be disturbing. However, while these crush stains certainly confirm the presence of bed bugs, they pose minimal health risks:
- The stain is from already processed blood, not fresh infectious blood.
- There are no contaminating mouthparts as with other insects.
- The spot is just absorbed bed bug blood, not absorbed human blood.
- No components of your blood have entered the bug’s body.
- It simply helps locate infestation areas without harm.
So while disgusting and inconvenient, a smear from crushing a bug after feeding is not a worrisome health issue and causes no significant exposure. It should prompt thorough inspection and control measures for bed bugs.
Conclusion
To summarize key points:
- Freshly fed bed bugs have red blood that digests within hours to yellowish or clear.
- Old dried bloodstains are brown or black.
- The color change happens rapidly thanks to their specialized digestion.
- Different species show similar blood colors.
- Crush stains are not sanitary risks, just evidence of bugs.
So in conclusion, while the blood colors and stains from bed bugs may seem alarming, they pose minimal health risks beyond serving as warning signs of an infestation. Being informed about the colors can help detect and eliminate bed bugs.