People who discover bed bugs in their home often wonder when the bugs were introduced. This is an important question as it could shed light on where the bugs originated by matching the timeframe of the infestation with overnight stays or visitation by guests. For small numbers of bed bugs, estimates can be relatively accurate. For large numbers (over 100), a minimum time can be set but the range of possible introduction dates would be quite large.

Bed bugs at 72 degrees F require about 7 weeks to develop from egg to adult. If only a couple of adults are present, it is most likely that the adults are the source of the infestation and their length of stay can be estimated from the development of immatures. Calculate about 10 days for egg hatch and 1 week per instar. For example, if the most mature immatures are 3rd instar, add 7 days each for the first and second instars to 10 days for egg development to estimate that the bedbugs were probably introduced between 24 and 1 month prior to discovery.

Bed bugs produce eggs at about the rate of 2 eggs per day. An introduction of 3-5 female bed bugs would produce of population of 6-10 adults at about 7 weeks and rise to 40 – 70 by 8 weeks after introduction. After 14 weeks,the progeny of the second generation become adults and the population of adults can rapidly rise from rise from a couple hundred to over a thousand.  A population of 1000 bed bugs is likely to be in existence well over 14 weeks.  How much longer is difficult to estimate.