Heat treatment is one of the most effective methods to control bed bugs, but it’s not a foolproof solution on its own.
By their very nature, bed bugs prefer to live in the cracks and crevices of mattresses, upholstered furniture, baseboards and other nooks and crannies close to where people rest. Turning up the heat can send them scurrying deeper into walls and upholstery where it’s cooler and the heat can’t penetrate. Cranking the heat up even higher isn’t a solution either, because this can damage a home and its contents.
Without a lethal dose of heat, bed bugs are free to resume their normal, blood-sucking activities, even if it takes them a couple of weeks to recover. Neither does heat treatment control the bed bugs that get reintroduced to the premises; it’s more of a one-time solution to the problem. Bed bugs still can travel through the wall of a neighboring apartment or be carried in on a piece of luggage or clothing and grow into a larger infestation.
The best approach is to mount multiple attacks on bed bugs by combining heat treatments with the application of pesticides, say Purdue University researchers, who tested the potential of bed bugs to develop heat resistance.
The Purdue study, led by entomologist Ameya Gondhalekar and doctoral student Aaron Ashbrook, was published in the journal PLOS One in February 2019. It determined that bed bugs’ ability to develop substantial resistance to heat is low.
And while that’s good news for pest management professionals, the researchers say heat treatment alone may not deliver the long-term results that customers expect.
“It is important to remember that heat is not the only method for bed bug control,” says Ashbrook in a news release. “And combining treatment techniques gives you the best chance of eliminating all the bed bugs in an infestation.”
Kevin Thorn, president of Thorn Pest Solutions in Pleasant Grove, Utah, was an early adopter of heat treatment for bed bug control. Bed bug control services account for about 30 percent of the company’s overall revenue.
“Heat is amazing at knock down. I really works against resistant bed bugs. It really does a great job, but there is no residual,” he says. As such, technicians at Thorn Pest Solutions apply a liquid insecticide to areas where bed bugs normally harbor and to baseboards before turning up the heat.
Bed bugs are activated by heat -- “they get excited” and move around, explains Thorn – until it gets too hot and they start to hunker down. “When you’ve got that movement it’s just really nice to have that product down and then when the heat goes away you still have that residual,” he says.
The bed bugs attempting to escape the heat, such as by retreating behind baseboards and burrowing deeper into mattresses and box springs, come in contact with an insecticide’s active ingredients and die.
Neither does heat treatment degrade the efficacy of insecticides. A study by the University of Florida in 2011 found that applying insecticides before heat treating increases bed bug mortality. Heat treatment didn’t change the active ingredients' crystalline structure or affect product volatility. In most cases, insecticides worked better after heat treatment than before, found the study.
Thorn urged pest management professionals to follow best practices for heat treatment to reduce cold spots where bed bugs can survive treatment. This includes rotating items in the room during treatment, using fans to disperse heat more evenly and using monitors to ensure temperatures remain at the appropriate level for the required amount of time.
Even so, “in some structures there are just some places you are not going to get hot,” such as floors on a concrete slab, he says. It’s important to identify these spots beforehand and take steps to ensure control. Pesticides are a solution for difficult-to-heat places, says Thorn.