Bedbugs feed on human blood so if the bug is squished after it has fed, there will be a spot of blood left behind. Dark, rust-colored spots on bedding or nearby walls. These spots could be bedbug excrement.Click to see full answer. Similarly, what bugs are mistaken for bed bugs? The following is a list of five bugs that are often mistaken for bed bugs. Bat bugs. Color: Brown. Spider beetles. Color: May range from pale brownish yellow to reddish brown to almost black. Booklice. Color: Pale brown or creamy yellow. Carpet beetles. Color: Black with white pattern and orange/red scales. Fleas. One may also ask, how do bed bugs get blood? Bedbugs feed on the blood of humans (though some species have a taste for other mammals and birds, too) by inserting a sharp proboscis, or beak, into the victim’s skin. The critters become engorged with blood in about 10 minutes, which fills them up for days. what color is bed bug blood? When an adult bed bug has not taken a blood meal they are reddish-brown. However, once they consume a meal, their color will be bright red because their body is now filled with blood.Why do bed bugs have black blood?After feeding bed bugs will digest the blood meal and excrete it as a dark liquid that will appear as dark spots. The dark “spotting” of excreted blood can be found on box springs, mattresses, bed sheets, furniture or any other place that bed bugs are active. Bed bug engorged with blood.