Bed Bug Droppings

Blood spots, or smears, from bed bugs.

Bed bug droppings are sometimes the first sign of a bed bug infestation. Bed bugs only feed on blood and they prefer human blood. These insects will feed on blood of other animals, but it is speculated that human blood offers the best nutrition as well as the most suitable source for obtaining blood. Body temperatures, carbon dioxide, and scent are all assumed to play a role.

Other insects feed on blood, but in some species, only the female feeds on blood. This is necessary to lay eggs. When not laying eggs, these insects might feed on pollen and other food sources.

Bed bugs, of both genders, on the other hand, feed exclusively on blood, consuming blood throughout their development. From the time that the young hatch from eggs to the end of their lives, both male and female bed bugs feed on blood. Each stage of life, or instar, may have multiple meals of blood.

After feeding, the bed bug may void or drop partially digested blood on surfaces. They can also do this even as they feed. Thus they can feed on blood and at the same time, deposit thick tarry droppings from the hind end of the abdomen.

Bed bug droppings have been described as tarry in color, although, the normal color is dark red to black. As the blood ages, it can darken. As the blood droppings are usually deposited during or after feeding, these droppings can appear as dark smears on bed linens, upholstery, furniture, or floor coverings. If the bed bugs are not disturbed and droppings are deposited on a hard surface such as a wall, they appear as small dark dots and there is no evidence of smearing.

Bed bug droppings also usually appear near the bed bug hiding places. These can be near electrical, phone, or computer outlets, wall switches, baseboards, overhead ceiling/wall joints, or on furniture. Smears can be found on softer fabrics such as drapes, towels, and clothing.

Blood smears on mattress:
picture of blood smears from bed bugs on mattress