By Chris Williams on February 6, 2012.
I was recently sent to a job to inspect for Bed Bugs. Previous tenants had been treated for bed bugs and have moved out. Management wanted to know two things: How long has the unit been infested, and were there any live beg bugs. Inspection for bed bugs can be difficult as most units are full of furniture and belongings, this unit was vacant and empty. With full access to all areas of the unit the extent of the infestation was more clearly defined.
Bed bugs, the scourge of the rental industry, are small insects that feed exclusively on human blood. Long lived and easily spread, bed bugs secretive lifestyle makes detection difficult. Relatively few bed bugs start an infestation. In fact, if a male bed bug is the only hitchhiker, no infestation will develop. Only female bed bugs are able to lay eggs. A mated female can lay around 3 eggs a day if feeding is available, laying more than 300 eggs in her lifetime. Small white eggs are cemented to discrete surfaces, near a host, and hatch in about 10 days. Nymphs resemble adults but are much smaller. In order to grow, or molt, nymphs must acquire a blood meal. Depending on the temperature, it takes nymphs about 100 days for the five molts to occur before mating can take place. Roughly 1.5-2 months are required for a complete cycle from egg to mated adult bed bug. Adult bed bugs live about 10 months, although without a host, bed bugs may live over a year.
Bed bug infestations develop slowly. At first very few insects are present, feeding intermittently on the host and may not be noticed. Bites are sometimes overlooked or blamed on some other pest species like spiders. Secretive adults may not be noticed as they feed on sleeping hosts. Over time though, evidence builds up. Bed bugs are gregarious, and can be found living side by side in harborage sites. Great numbers of nymphs and adults can be found together. As these sites become more active, females will migrate to areas of less activity to lay eggs. Male bed bugs want to mate constantly with females, driving them away. This behavior is believed to be what makes bed bugs “spread out” into new areas. Large populations also use up more and more of the hiding spaces near the host, and are forced to seek shelter farther from the feeding site. All the while the bed bugs are pooping. Bed bug feces is little more that partially digested human blood. Fecal spots form as the bed bugs move about and accumulate in and around the harborage sites. Fecal spots are usually clustered, and may have a small “smear” at one side, indicating the direction of the bed bug’s travel. In heavy infestations there may even be a discernable, almost sweet odor, due to large amounts of feces and aggregation secretions. As bed bugs molt during the growth process, the smaller old skin is shed and a new larger skin forms. These skins are also left where they fall and may accumulate over time. In heavy infestations, there may be considerable numbers of these cast skins.
Now, back in the unit to be inspected, I am looking for evidence. I begin with a cursory look around. With a bright flashlight, pliers, and a screwdriver in hand I start with the ceiling edges and walls. As harborage sites become full, bed bugs will end up in corners and on walls. Right away I begin to notice some fecal spots on door frames and at lower closet edges. No activity behind outlet covers, or under carpet in the 2 bedrooms, 12-25 dead bed bugs noted on the bed room floors, some fecal spots on lower closet door and door frames, no live activity. Bases of all 3 hall closet door frames also had fecal spots, dead bed bugs, no live activity. As I began to examine the living room, there seemed to be more and more dead bed bugs, and fecal spotting, increasing as I got over to the baseboard radiator. Fecal spotting all over the metal housing and adjacent molding told me I was getting warm. When I dismantled the housing and pulled the carpet out from under it I hit pay dirt. 1000’s of cast skins, large pockets of blood stained carpet(major harborage site), and hundreds of dead bed bugs were deposited under the carpet and heating unit. There must have been a couch or bed right there. As the infestation grew, the bed bugs spread out along the floor edge and eventually found the bed rooms, where there was much less fecal spotting etc. In my opinion, the focal point of the infestation was the living room. As far as a time table is concerned, based on the life cycle, amount of fecal spotting, and the number of cast skins noted, the infestation was more than a year old, maybe older. 2 live bed bugs were found, although upside down, on the kitchen floor. This indicates that the treatment was working, and that bed bug control is almost complete. My recommendation was to re-treat the unit prior to new tenants moving in to ensure that the infestation is gone completely.