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.<