Forty Years of Decline After Resistance Appeared: Why the Standard Explanation for the Bed Bug Resurgence Does Not Fit the Dates

1. Introduction: a question the trade rarely asks properly

Ask anybody in this industry why bed bugs came back and you get a one-line answer: they banned DDT. It is repeated in trade literature, in news coverage, and by technicians.

It does not survive the dates.

1.1 Why the answer matters commercially

Because an industry that misdiagnoses why a pest returned will misjudge what keeps it away. The explanation this article settles on has direct consequences for how a building is protected, which is §21.

It also bears on how a client is advised. A hotel manager who believes the cause was a pesticide ban concludes that nothing can be done. One who understands that a barrier was removed and never replaced concludes that something can, which is a materially different conversation.

2. What normal looked like before

The baseline, which modern readers consistently underestimate.

The insect is mentioned in medieval European texts and in classical Greek writings back to the time of Aristotle,² and had lived on human blood since at least the Bronze Age.³

British surveys from the 1930s found infestations in roughly a third of working-class housing in some London boroughs.³ In the early twentieth century the majority of Americans had seen one and most had been bitten.⁵

2.1 Why the baseline is hard to imagine now

A pest that most people in a country have seen and most have been bitten by⁵ is not a pest control problem in the modern sense. There is no uninfested comparison to aspire to and no stigma available, because everybody has them.

2.2 A third of the housing stock

That is not an infestation problem. It is a condition of life, comparable to damp or draughts, which people managed rather than eliminated.

Understanding that changes how the disappearance should be read. It was not a pest being suppressed; it was a near-universal parasite being removed from an entire society within about a decade.

3. The collapse

What happened, and how fast.

Following the introduction of the compound in the 1950s, bedbugs virtually disappeared in the United States.² Wide and continued use of DDT and then later other insecticides such as malathion reduced substantially the incidence of bed bugs during the post-World War II period.¹

It was cheap, persistent, and lethal to a broad spread of insects, and was sprayed directly onto bed frames, baseboards, and mattress ticking through the late 1940s and into the 1950s.³

4. Why the chemistry suited this insect

The mechanism, which is the most elegant thing in this history.

Untreated insects could be killed by insects crawling on DDT-treated surfaces while searching for a host or a refuge at nighttime.¹

4.1 The behaviour delivered the dose

A bed bug must leave its harbourage, cross a surface, feed, and return. That journey is obligatory and it is repeated. A persistent residue on the route between refuge and host does not need to be found; it needs only to be crossed.

This journal's article on bed bug chemical ecology described aggregation and dispersal behaviour in detail, and it is precisely that behaviour which made a residual barrier so effective against this species and so much less effective against a pest that does not commute.

4.2 Why this matters for what came later

If the control depended on treated surfaces lying across a compulsory route, then removing the treated surfaces removes the control, whether or not the insect is resistant to what used to be on them.

That is the hinge of this article and it returns in §11.

5. How complete it was

The degree of the disappearance, which is easy to understate.

The species was so thoroughly beaten back in American and European homes by the early 1950s that entomologists at the time openly wondered whether the species was on its way to becoming a rarity in developed countries. A young pest-control worker in London or Chicago could go an entire career without seeing one. By 1960, entomology textbooks were describing bedbugs in the past tense.³

5.1 What entomologists got wrong

They were wondering whether a species that had lived on human blood since the Bronze Age was about to become a rarity,³ on the evidence of about ten years of observation.

It is a useful corrective for anybody now describing a pest as controlled. The evidence for disappearance was excellent and the conclusion was wrong, because it read a control measure as a property of the organism.

5.2 The career point is the operational one

An entire professional generation acquired no field experience of this insect. When it returned, the people expected to deal with it had never seen an infestation, and §19 shows the research literature was in the same position.

6. Where they survived

The refuge populations, which matter for what came back.

By the middle 1950s bed bugs had changed from a major household pest to an occasional pest in socially depressed settings or other unusual circumstances. A rare bed bug problem might show up in shelters, prisons, youth hostels, or cabins but almost never in homes or hotels.⁴

Sporadic infestations occurring in dwellings with high occupant turnover and questionable sanitation conditions were eliminated with organophosphates and carbamate insecticides.¹

6.1 Why any survived at all

Because no campaign reaches everywhere. Treatment was concentrated in ordinary housing and commercial accommodation, and the settings named are the ones least likely to receive scheduled private pest control.

The insect did not need to hold out against the chemistry, though §15 shows some did. It needed only somewhere the chemistry did not routinely go.

6.2 The common feature of those settings

High occupant turnover. People arriving and leaving with their belongings, which is the mechanism by which a flightless insect moves between buildings, and which is also the defining feature of the hotels and apartment blocks where §10 says the resurgence began.

Those settings never stopped being reservoirs, which means the resurgence did not require reintroduction from anywhere. The population was already present and constrained.

7. The fact that breaks the standard story

Stated plainly because everything else follows from it.

After the compound came into wide use, several studies reported resistance of bed bug populations to these compounds. And despite the evidence of developing resistance, bed bug infestations continued to decrease dramatically in the USA and other developed countries over the next 40 years.¹

A separate account puts it the same way: although DDT resistance appeared within a few years, control remained effective with the other chlorinated hydrocarbons, particularly lindane, and eventually the organophosphate insecticide malathion.⁴

8. What that rules out

The inference, which is ours and which we think is unavoidable.

Resistance to the original compound cannot be the trigger for a resurgence that began roughly four decades after that resistance was documented. A cause has to precede its effect closely enough to be doing work, and this one was already fully present throughout the period of steepest decline.

8.1 The related claim that also fails

That the ban caused the return. One account dates the United States ban to 1972.⁶ The resurgence is dated to the late 1990s.¹

Twenty-five years is a long lag for a cause with no intervening mechanism, and §9 supplies what was holding the line in the meantime. A ban that is followed by two and a half decades of continued decline has not been shown to have caused anything.

8.2 What the failure of both claims leaves

That something else was suppressing bed bugs through the 1960s, 1970s and 1980s, and that whatever it was stopped in the 1990s.

9. What held the line instead

The succession of chemistries, which the sources are clear about.

Control remained effective with the other chlorinated hydrocarbons, particularly lindane, and eventually the organophosphate insecticide malathion.⁴ Sporadic infestations were eliminated with organophosphates and carbamate insecticides.¹

9.1 Four chemistries, one outcome

Chlorinated hydrocarbons, then lindane, then malathion, then organophosphates and carbamates.¹⁴ Each replaced its predecessor as resistance or regulation removed it.

9.2 The pattern this journal has named before

A sequence rather than a strategy: use a product until it fails, then reach for the next one. The rotation article set out why that is the default behaviour of an unmanaged market, and this is a forty-year worked example of it succeeding.

It succeeded because replacement compounds kept arriving. That supply is what §12 says nobody should assume will continue.

9.3 The delivery method stayed constant

Across all those chemistries, the method was the same: a residual deposit on surfaces in rooms where people sleep. The active ingredient changed repeatedly; the practice did not.

Which means the question worth asking is not when the chemistry changed, but when the practice did. Four different active ingredients over four decades produced one continuous outcome, so the active ingredient was not the variable that mattered.

10. The change in the mid-1990s

The answer, from an account that states it directly.

During the mid nineties, a dramatic shift took place in the practices of pest management. Treatments that were routinely scheduled for the baseboards in motels, hotels and apartments were replaced. The replacement was a targeted application of baits for other pests such as cockroaches and ants. Because of the residual pesticide application absence, the bugs traveled safely and freely from luggage to the bed.⁵

And the sentence that makes it fit: there is not any bait used for the blood feeding insects.⁵

10.1 The shift was industry-wide and deliberate

It is described as a dramatic shift in the practices of pest management rather than as a change by individual firms,⁵ and it happened across the developed world within a few years.

Which is what §17.1 requires: a cause operating simultaneously on four continents has to be something the industry did everywhere at once, and a change of standard method qualifies.

10.2 Why baiting replaced spraying

Because it was better. This journal's articles on horizontal transfer and on integrated pest management economics set out why bait outperformed broadcast residual treatment for cockroaches: it exploits social feeding, reaches harbourages a spray cannot, and places far less active ingredient into occupied space.

The shift was a genuine improvement in the practice of pest control, adopted for good reasons.

10.3 What was lost without anybody noticing

A bait works by being eaten. An insect that feeds only on blood will never eat one, which means the transition from residual spray to bait removed all incidental pressure on bed bugs at once.

Nobody had been treating for bed bugs. Everybody had been treating bed bugs anyway, as a side effect of treating for something else, and the side effect ended.

11. Why that explanation fits

Testing it against §7's chronology.

It is independent of resistance, so it is unaffected by resistance having appeared forty years earlier. It is independent of the ban, since the practice continued with replacement compounds for decades afterwards. And its date, the mid-1990s, sits immediately before a resurgence dated to the late 1990s.¹⁵

11.1 It also explains the mechanism

Section 4 established that control worked because a compulsory route lay across a treated surface. Baseboards in hotel and apartment bedrooms are that route. Removing the deposit removes the control without any change in the insect at all.

11.2 And it explains where the return started

Hotels, motels and apartments,⁴ which are exactly the premises the source names as having had scheduled baseboard treatment.⁵ The two lists are the same list, which is the strongest thing this article has in favour of the account.

A single-family house on no service contract had no such treatment to lose, which predicts that the resurgence should appear first in serviced commercial accommodation and spread outward. That is the reported pattern, and the inference is ours.

12. What it does not argue

An important limit, stated before anybody draws the wrong conclusion.

This is not an argument for returning to scheduled broadcast spraying of sleeping areas. The practice was abandoned because a better method existed for the target pest and because putting persistent residues across occupied bedrooms carries an exposure cost this journal has documented at length in the applicator and pollinator articles.

12.1 Why going back would not work anyway

The population that returned carries sodium channel resistance inherited from the survivors of the original campaigns,³ so a residual deposit of the modern equivalent chemistry meets an insect already selected against it.

The barrier worked in 1955 against a largely susceptible population. Rebuilding it in 2026 would reproduce the exposure cost without reproducing the effect.

12.2 The actual lesson

That a control which is working incidentally is invisible, and therefore gets removed without anyone costing what it was doing.

The same structure appears wherever a practice has a benefit nobody has attributed to it. An industry improving one thing removed a barrier it did not know it had built, and the bill arrived about five years later.

12.3 What replaced it properly

Monitoring, inspection, encasements, heat, and targeted treatment of harbourages, which are the subject of several other articles here. Those are better than a broadcast residual, and they require somebody to be looking, which a residual did not.

13. The travel explanation

The other common account, which is real and is usually overstated.

The resurgence is the result of increased global travel and a shift toward less-toxic pest control.⁷ One national housing ministry cited international travel and growing resistance to insecticide as the main causes.⁸ Another account has them appearing first in major cities such as Los Angeles and Miami due to people bringing them back over on airplanes.⁶

13.1 Where they reportedly appeared first

Major coastal cities with the heaviest international air traffic,⁶ which is what a travel-driven introduction would predict and is consistent with the mechanism in §13.2.

13.2 The behavioural finding that supports it

A study reported that the insects sought out human scents and snuggled up in worn clothes before tagging along home, explaining their meteoric spread around the world.⁸

That is a real mechanism for a flightless insect crossing continents, and it is the same aggregation cue this journal's chemical ecology article described being exploited by monitors.

14. Assessing it

How much weight travel should carry.

Travel explains dispersal. It does not explain establishment, because an insect arriving in a hotel room that is being treated on a schedule arrives on a treated surface.

14.1 The question travel cannot answer

International travel rose steadily from the 1950s onward. If travel alone were sufficient, the resurgence should have been gradual and should have begun decades earlier.

Instead the reported onset is sharp and late. Travel supplies the propagules; something else determined whether they survived arrival, and that is §10. This reasoning is ours.

14.2 The counter-case for travel

Air travel volumes did not rise smoothly. Deregulation, low-cost carriers and the growth of international tourism produced a steepening curve, and a threshold effect on an exponential is compatible with a sharp onset.

We do not have the passenger numbers to test that and would not want §14.1 read as a refutation. It is a reason to think travel alone is insufficient, not a demonstration that it is.

14.3 Where travel does the real work

In turning local outbreaks into a simultaneous international one. The survey in §17 found comparable figures across four continents at once, which is a signature of a connected system rather than of independent national events.

15. The inherited resistance

The genetic component, which is where the modern population differs from the historical one.

Genome studies show the resurgent bugs carry sodium-channel mutations inherited from the rare survivors of the original spraying campaigns.³ A 2016 study found that the reclusive, flightless creatures had become resistant to pesticides, further aiding their global conquest.⁸

15.1 What resistance actually explains

Not why they came back, for the reasons in §8. Why they were so difficult to remove once they had.

A population re-establishing in the 1990s met pyrethroids, which share the sodium channel target with the compound its ancestors had survived. This journal's article on layered resistance in this species covers the mechanisms and the additional ones that followed.

15.2 Why a mutation can sit idle for decades

Because a resistance allele confers no advantage when nothing is selecting for it, and this journal's cockroach article found fitness costs that make such alleles mildly disadvantageous in the absence of exposure. A gene that lets an insect survive a compound nobody is applying is simply a gene.

It persisted in the refuge populations of §6 because those populations were small, isolated and occasionally sprayed, which is the condition under which an existing resistance allele is maintained.

15.3 The chronological point restated

The mutations were inherited from survivors of campaigns conducted decades earlier.³ They were present in the refuge populations of §6 the entire time, doing nothing, because the populations were being held down by other means.

16. How the three fit together

The synthesis, which is ours.

Refuge populations persisted in high-turnover settings throughout, carrying resistance to the sodium channel chemistries. Travel moved them continuously and increasingly. And an incidental residual barrier in serviced accommodation prevented establishment until the mid-1990s, when it was replaced with bait for a different pest.

16.1 The shape of the argument

Three conditions had to hold simultaneously for the resurgence to occur, and each had a different date. The populations were continuous, travel rose over decades, and the barrier came down in one period.

When two conditions are slow-moving and one changes sharply, the sharp one sets the timing. That is why §10 carries the explanatory weight even though it is the least discussed of the three.

16.2 Each account is necessary and none is sufficient

Without the refuge populations there is nothing to spread. Without travel the spread is local. Without the removal of the barrier the arrivals do not establish. Without inherited resistance the new infestations are treatable with the first thing anybody reaches for.

16.3 Why the single-cause versions persist

Because each is true as far as it goes and each is easier to say. The ban explanation additionally flatters everyone: it locates the cause in regulation rather than in a decision the industry made itself.

17. The scale of the return

The numbers, from a survey with international coverage.

A survey conducted by a national pest management association with a university had respondents from 43 countries. Of 521 responding U.S. pest management companies, 95 per cent reported encountering a bedbug infestation in the past year, with Canada at 98 per cent, Europe at 92 per cent, and Africa and the Middle East at 90 per cent. By comparison, before 2000 only 25 per cent of U.S. survey respondents reported bedbug infestations.²

17.1 What a four-region agreement implies

Ninety-five, ninety-eight, ninety-two and ninety per cent across the United States, Canada, Europe and Africa with the Middle East.² Those are not four national stories that happened to coincide.

A resurgence arriving simultaneously across continents points at something operating on all of them at once, which is §14.2's argument, and at practices that changed across the developed world together, which is §10.

17.2 The Canadian figure

Ninety-eight per cent, the highest of the four regions reported.² Whatever happened, it did not happen less here.

18. What changed about who gets them

The social inversion, which is the part that matters for how people are treated.

In the mid-1990s they began appearing in hotels and motels, even premium ones, and in apartments, single-family homes, nursing homes, and hospitals, with media exposés on bed bug attacks in five star hotels.⁴

18.1 What the earlier pattern was actually measuring

Not cleanliness. The settings where they persisted share high occupant turnover and low expenditure on scheduled pest control,¹⁷ and the second of those is a budget rather than a behaviour.

So the mid-century association between infestation and deprivation was largely an association between infestation and not having a service contract, which is an entirely different fact about a household.

18.2 Why the inversion matters

Through the middle of the century an infestation was confined to settings characterised in the literature of the time as socially depressed,⁴ which attached a stigma that this journal's article on the psychological burden of infestation found persisting long after the epidemiology stopped supporting it.

The resurgence is indiscriminate. That is the single most useful fact to give a distressed client, and it is the direct consequence of the mechanism in §10: the barrier that came down was in serviced accommodation, which is to say in exactly the places that had been protected.

19. The research gap

What the fifty-year absence cost.

The scarcity of bed bugs in many countries over the last 50 years has resulted in a lack of modern research into the toxicology of this pest. Although they resurged in the late 1990s, published research related to insecticides has lagged behind and only began to appear in 2006.¹

19.1 What fifty years of absence removed

Not just published toxicology. Rearing colonies, standard bioassay protocols, baseline susceptibility data and researchers who had worked on the species.

A resistance finding needs a susceptible reference strain to compare against, and this journal's diagnostics article set out why that reference is the hard part. Half a century without the pest means half a century without anybody maintaining one.

19.2 A decade of nothing

The resurgence was underway for roughly ten years before the research literature responded, and the trigger was that the difficulty in controlling bed bugs triggered the interest of both private and academic sectors.¹

Research followed commercial pain rather than preceding it, which is the same incentive structure this journal has described in several other contexts.

20. Government responses

How seriously this was taken once it was recognised.

Public health and environmental agencies issued a joint statement on the resurgence of bed bugs.⁷ One national government launched a campaign, complete with emergency number, to combat an influx, warning that we can all be affected and publishing prevention and treatment advice.⁸

In one city, 11,000 residents filed official complaints in a single year.⁷

20.1 The scale a complaint figure implies

Eleven thousand formal complaints in one city in one year⁷ is the count of people who reached the point of filing with an authority.

Most infestations are never reported to anybody, which this journal's articles on detection and on tenancy responsibility both argued. The filed number is a floor on the real one and the ratio between them is unknown.

20.2 The public health framing

Worth noting that they do not transmit disease.⁸ A national emergency line for an insect with no documented disease transmission is a response to distress and economic damage rather than to infection, which this journal's article on psychological burden would say is entirely proportionate.

21. What the history is good for

An incidental control is still a control. Work out what a practice is doing besides its stated purpose before changing it.

The route is the target. What worked against this insect was treating the path between harbourage and host.¹

Travel disperses; conditions establish. Which is why a building's own defences determine its outcome.

Resistance explains difficulty, not arrival. The mutations predate the resurgence by decades.³

Nobody is exempt. Premium hotels and hospitals included.⁴

Monitoring replaces what the residue used to do. A barrier works unattended; an inspection regime does not, and that is the trade this industry made.

22. Limitations and open questions

The practice-shift account rests on one source. The direct statement that scheduled baseboard treatment in hotels and apartments was replaced by targeted baiting comes from a single trade page, and we have not found it corroborated in peer-reviewed literature.⁵ It is the load-bearing claim of §10 and §11 and it deserves better support than we can give it.

Several sources are popular or commercial. A popular science article, two pest control company pages and a news agency report, used for historical narrative rather than for evidential claims.³⁵⁶⁸

The survey is self-reported by firms. Firms encountering an infestation is a measure of professional experience rather than of prevalence, and a resurgence generating publicity will raise reporting independently of incidence.²

The 25 per cent baseline is not directly comparable. It comes from a different question asked at a different time and is reported as a comparison rather than as a matched series.²

We have not established dates precisely. Resistance appearing within a few years, a forty-year decline and a late-1990s resurgence are the sources' characterisations, and we have not gone to the primary studies behind any of them.¹

No Manitoba material. We found nothing on when and how the resurgence reached this province, which would be a useful piece of local history and does not appear to have been written.

Sections 2.1, 4.1, 4.2, 6.1, 8, 9.1, 9.2, 10.2, 11.2, 12, 14.1, 15.1, 16 and 18.1 are our reasoning. The baseline framing, the route argument, the refuge inference, the chronological refutation, the sequence comparison, the practice-against-chemistry distinction, the bait limitation, the geography prediction, the lesson drawn, the travel assessment, the role assigned to resistance, the synthesis and the stigma argument are ours rather than sourced positions.

23. Conclusion

An insect found in roughly a third of working-class housing in some London boroughs in the 1930s was being written about in the past tense by 1960.³ Resistance to the compound responsible was reported within a few years, and infestations went on falling dramatically for another forty, held by lindane, then malathion, then organophosphates and carbamates.¹⁴ So the story everybody tells, that a ban let them back, has a twenty-five year hole in the middle of it.

What stayed constant across all those chemistries was the practice: a residual deposit on baseboards in rooms where people sleep, lying across the only route a bed bug has between its harbourage and its host.¹ In the mid-1990s that scheduled treatment was replaced in hotels, motels and apartments by targeted baiting for cockroaches and ants, which was a better method for those pests and no method at all for a blood feeder.⁵ Travel supplied the arrivals, inherited sodium channel mutations made them hard to remove, and the barrier that had been stopping them was gone.

The useful part is not the blame. It is that the industry had built a defence it did not know it had, and removed it while improving something else, and nobody costed the loss because nobody had ever counted the benefit. That is worth holding onto, because the same thing is presumably true right now of some practice currently in use, and the way to find out is to ask what each routine treatment is doing besides the thing it is aimed at.

References

1. Moving From the Old to the New: Insecticide Research on Bed Bugs since the Resurgence. PubMed Central PMC4553459. Principal source. Used for the statements that insecticides have historically been the principal means of controlling bed bug infestations; that untreated insects could be killed by crawling on DDT-treated surfaces while searching for a host or a refuge at nighttime; that wide and continued use of DDT and later insecticides such as malathion substantially reduced incidence during the post-war period; that soon afterwards several studies reported resistance of bed bug populations to these compounds; that despite the evidence of developing resistance, infestations continued to decrease dramatically in the United States and other developed countries over the next forty years; that sporadic infestations in dwellings with high occupant turnover and questionable sanitation were eliminated with organophosphate and carbamate insecticides; that the scarcity of bed bugs in many countries over the last fifty years resulted in a lack of modern research into the toxicology of this pest; that although bed bugs resurged in the late 1990s, published research related to insecticides lagged behind and only began to appear in 2006; and that the difficulty in controlling bed bugs triggered the interest of both private and academic sectors. https://pmc.ncbi.nlm.nih.gov/articles/PMC4553459/
2. Invasion of the Bedbugs. Environmental Health Perspectives, reproduced at PubMed Central PMC2957946. Used for the statements that bed bugs are mentioned in medieval European texts and in classical Greek writings back to the time of Aristotle; that following the introduction of DDT in the 1950s bedbugs virtually disappeared in the United States; and for the survey conducted by a national pest management association with a university, with respondents from 43 countries, in which of 521 responding United States pest management companies 95 per cent reported encountering a bedbug infestation in the past year, with similar figures for Canada at 98 per cent, Europe at 92 per cent and Africa and the Middle East at 90 per cent, compared with only 25 per cent of United States survey respondents reporting bedbug infestations before 2000. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2957946/
3. Popular science account of the bedbug disappearance and comeback. General-interest publication, cited for historical narrative rather than as an evidential source. Used for the statements that the insect had lived on human blood since at least the Bronze Age; that British surveys from the 1930s found infestations in roughly a third of working-class housing in some London boroughs; that the species was so thoroughly beaten back in American and European homes by the early 1950s that entomologists openly wondered whether it was becoming a rarity in developed countries; that a young pest-control worker in London or Chicago could go an entire career without seeing one; that the compound was cheap, persistent and lethal to a broad spread of insects and was sprayed directly onto bed frames, baseboards and mattress ticking through the late 1940s and into the 1950s; that by 1960 entomology textbooks were describing bedbugs in the past tense; and that genome studies show the resurgent bugs carry sodium-channel mutations inherited from the rare survivors of the original spraying campaigns. https://terradaily.com/j-in-the-1930s-bedbugs-had-nearly-vanished-from-developed-homes-and-their-global-comeback-since-the-late-1990s-is-traced-largely-to-the-insects-evolving-resistance-to-the-very-insecticides-that-once-w/
4. Bed Bug History. Technical newsletter for pest management professionals. Trade source, cited as attributed material. Used for the statements that although DDT resistance appeared within a few years, control remained effective with other chlorinated hydrocarbons, particularly lindane, and eventually the organophosphate insecticide malathion; that by the middle 1950s bed bugs had changed from a major household pest to an occasional pest in socially depressed settings or other unusual circumstances, with a rare problem showing up in shelters, prisons, youth hostels or cabins but almost never in homes or hotels; and that in the mid to late 1990s bed bugs began appearing more and more in hotels and motels, even premium ones, and in apartments, single-family homes, nursing homes and hospitals, with media exposés on infestations in five-star hotels and a clear and major resurgence throughout much of the world. https://www.techletter.com/Archive/Technical%20Articles/bedbugcomeback.html
5. The History of Bed Bugs. Pest control information website. Commercial source, cited as attributed material; this is the single source for the practice-shift account and its limitations are recorded in §22. Used for the statements that in the early twentieth century the majority of Americans had seen a bed bug and most had been bitten; that during the mid-1990s a dramatic shift took place in the practices of pest management, in which treatments routinely scheduled for the baseboards in motels, hotels and apartments were replaced by targeted application of baits for other pests such as cockroaches and ants; that because of the absence of residual pesticide application the bugs travelled safely and freely from luggage to the bed; that there is not any bait used for the blood feeding insects; and that a lack of community awareness assists their transfer from one location to another. https://www.bedbugs.org/the-history-of-bed-bugs/
6. Tracing the History of Bed Bugs and Their Modern Comeback. Pest control company page. Commercial source, cited as attributed material. Used for the account that the compound was made available for agricultural use in 1945 and played a large role in pest control in the 1940s and 1950s, eliminating bed bugs as a side effect of mosquito control; that concerns about its toxicity surfaced as its use became common, including potential harm to benign insects and to humans; that hearings were held in 1971 and 1972 and the compound was banned in the United States in 1972; and that bed bugs resurfaced in America in the 1990s largely due to increased travel, appearing first in major cities such as Los Angeles and Miami through air travel before spreading nationally. https://bedbugbbq.com/tracing-the-history-of-bed-bugs-and-their-modern-comeback/
7. Patent specification background section, and an educational resource on evolution in urban pests. Used for the statement that the resurgence of insect pests such as bedbugs is believed to be the result of increased global travel and a shift toward less-toxic pest control, and that bed bugs are most frequently found in dwellings with a high rate of occupant turnover such as hotels, motels, hostels, dormitories, shelters, apartment complexes, tenements and prisons; and for the report that federal public health and environmental agencies issued a joint statement on the resurgence of bed bugs, and that eleven thousand residents of one city filed official complaints about the insects in a single year. https://evolution.berkeley.edu/evo-news/bed-bugs-bite-back-thanks-to-evolution/
8. News agency report on a national anti-bed-bug campaign. Press source, cited as attributed material. Used for the report that a national government launched a campaign complete with an emergency number to combat an influx of bedbugs in homes and hotels; that after disappearing in the 1950s the insects made a resurgence, with the housing ministry citing international travel and growing resistance to insecticide as the main causes; that the government warned that everyone can be affected and published prevention and treatment advice; that the pest posed only a minor nuisance after the war because of widespread insecticide use; that by the late 1990s they were thriving in New York and a 2010 outbreak reached high-end apartment buildings, hotels and retail premises; that a 2016 study found the insects had become resistant to pesticides; that a study the following year reported they sought out human scents and settled in worn clothes before travelling home with people; and that they do not transmit disease. https://www.malaymail.com/news/life/2020/02/21/france-launches-anti-bed-bug-offensive/1839453