Bed bugs often congregate along seams, folds and edges of beds and upholstered furniture. (Photo: M.F. Potter)

Editor’s Note: This article was reprinted with permission from Techletter, a biweekly training letter for professional pest control technicians from Pinto & Associates.

The only way that you can declare that there is an active infestation of bed bugs is to find live bed bugs or viable (able to hatch) eggs. There are many other signs of a bed bug infestation such as shed skins, blood spots or fecal spots, but these by themselves only show that there was a bed bug infestation at some time. That infestation could still be active, or it could have been eliminated or it could have died out on its own. The following are signs of a bed bug infestation:

1) Live Bed Bugs. You must find one or more live bed bugs (or healthy, unhatched eggs) before you can say there is a bed bug problem at the site today. Anyone can find live bed bugs in a heavy infestation, but live bugs are difficult to find in the earlier stages of an infestation or when there is only a small population of bed bugs. In addition to your visual inspection, there are detection tools available such as bed bug monitors and traps, and canine scent detection (bed bug-sniffing dogs). All of these detection tools can find live bed bugs when used properly, but all have limitations and significant error rates.

2) Shed Skins and Dead Bed Bugs. In order to grow, a bed bug nymph will molt, or shed its skin, five times. The old exoskeleton that is left behind is tough and long-lasting. The empty, shed skins are the same general size and shape of the bugs that shed them except they are empty and translucent. Be careful that you don’t confuse shed bed bug skins with those of cockroach nymphs or dermestid beetles. Good bed bug hiding places will often have a large accumulation of these shed skins.

Finding bed bug shed skins confirms that there were bed bugs at the location at one time. Inspect for live bed bugs immediately around the area where you found the skins since it is now a known bed bug harborage site. Look at the skins closely because small bed bug nymphs sometimes hide inside the shed skins of larger nymphs and adult females sometimes deposit their eggs in shed skins.

As with shed skins, finding dead bed bugs only confirms that bed bugs were at the location at some time in the past. The carcass of a bed bug remains intact for a long time, for many months or perhaps even years.

3) Bloodstains. Bloodstains are not the same as bed bug fecal spots (see later in article). Brown or red-rusty blood spots found on sheets, pillowcases and clothing are from both bed bugs and their victim. Blood often drips out of the anus of a bed bug just before it completes feeding on its host. Then, as the bug pulls out its “beak,” the person’s bite wound typically bleeds a little.

But, bloodstains on bedding are not, by themselves, indicative of a bed bug infestation, either past or present. Other spilled liquids leave brown or rusty stains and not all bloodstains in a bed are caused by bed bugs. Bloodstains do not easily wash out of fabric so you can’t estimate their age. You also may find blood smears on the wall, usually located next to the bed. These are from residents smashing recently fed bed bugs.

4) Fecal Spots. The digested blood in the gut of a bed bug is deposited as semi-liquid, black feces. As the feces dry, it leaves behind a black, slightly raised spot. Bed bug fecal spots look somewhat like those left by the German cockroach, but they feel smooth rather than rough-textured. If you wet a bed bug fecal spot, it will smear, while the fecal spot of a cockroach will not.

You often will find large numbers of fecal spots in bed bug harborage sites such as along seams of mattresses. Fecal spots are useful for pinpointing bed bug activity areas and potential treatment sites. But as with bloodstains, fecal spots are long-lasting and may be from a previous infestation of bed bugs.

5) Bed Bug Eggs. Bed bug eggs are small, translucent white and difficult to see, especially when they are inside cracks, crevices, or holes or laid on light-colored surfaces. A female bed bug lays 1 to 3 eggs each day that will hatch in 7 to 10 days at room temperature. The eggs are covered with a sticky substance that attaches them to rough surfaces. Eggs are often found in clumps in harborage sites, but since females often wander, isolated eggs can be found far from the bed. These isolated eggs are very hard to find, hidden inside a screw slot, fabric seam or under the edge of a chip of paint.

Viable eggs confirm active bed bugs, or at least the potential for active bed bugs once they hatch. You can only be sure that an egg is viable once it hatches, but there are indications of egg health. Viable eggs are white and plump, not dried up or shriveled. Two or three days before hatching, two bright red eye spots will appear inside near the cap end of a viable egg. A bed bug egg that has already hatched will have the top cap end opened, no embryo inside and may be crumpled-looking.

The owners are well-known industry consultants and co-owners of Pinto & Associates.