Bed bugs bite back
Photo credit: Gary Alpert, Harvard University, Bugwood.org
Go back far enough in time and one in four homes was said to be infested with bed bugs. By the 1970s the use of modern insecticides meant they were no longer a common problem. More recently, however, bed bug populations have again begun to flourish – due to increased domestic and foreign travel, a lack of public awareness, the discontinued use of a number of insecticides and, of course, the development of resistance. In London, some operators have reported over 100% increase in call-outs for bed bugs during the past year.
For hotels and residential homes, the cost of bed bugs can include room downtime; disposal and replacement of infested items and staff time to prepare and reset a treated room. Furthermore, there are the other ‘hidden’ costs that may include a tarnished reputation, loss of business and potential legal action, with hefty fines.
Customer research has highlighted 80% of hotel visitors were concerned about finding bed bugs and 12% of travellers had altered or cancelled trips due to concerns about bed bugs.
Bug life creates challenges
Bed bugs are nocturnal parasites. They feed exclusively on blood and prefer humans to other potential hosts. Roughly 20% of people display an allergic response to bed bug bites – hence not all visitors to a hotel room may suffer, which makes pinpointing an infestation more difficult.
Adult bed bugs are around five to six millimetres long – about the size, shape and colour of an apple seed. After a blood meal, the adults may increase up to nine millimetres in length. Nymphs, the young stages of the bed bug life-cycle, are slightly smaller and virtually colourless when they first hatch becoming darker as they mature.
Bed bugs go through a series of five moults before reaching the adult stage. A feed on blood is required to moult from one stage to the next. Complete development, from egg to adult, can take as little as six weeks but, at typical bedroom temperatures of 18°C, it will take 16 weeks for the full cycle.
Adult bed bugs can crawl relatively long distances when seeking refuge or a host.
Studies in hotels have shown that when one room is infested, bed bugs can quickly spread to adjoining rooms – either through physical movement or transfer during the cleaning process.
Bed bugs avoid light and prefer to reside in tight cracks and crevices near a potential host. Due to their reclusive nature, it is difficult to inspect for and treat infestations.
And since bed bugs are transferred via infested personal belongings, it is virtually impossible to prevent their entry, or re-entry, into rooms.
Bed bug facts
- Bed bugs have been a nuisance to humans for thousands of years. Found in and around sleeping areas, bed bugs feed on human blood. Bites are typically found in small clusters or rows on the upper torso or other areas of the body that are in contact with bedding.
- Adults are usually found hiding in and around the mattress, box spring and frame of beds. However, bed bugs are very mobile and can hide in furniture, luggage, lamps, picture frames, curtains, even under switch plates, wallpaper and carpet edges. They are also excellent hitchhikers, which has contributed to their global resurgence.
- An adult bed bug can typically survive ten months without feeding, or longer at lower temperatures.
- A single bed bug can lay as many as 500 eggs in its lifetime of up to a year.
- Bed bug bites are typically painless with no lasting implications. However, they can cause an allergic reaction in some people leaving an itchy bump or welt that lasts for several days. There is some evidence bites may be linked to Chagas disease.
- Bed bugs feed on exposed skin for five to ten minutes until they're full. After feeding, they hide in secluded places, such as under mattress seams and behind headboards, for up to ten days before they need to feed again.
Finding your foe
There are four commonly used methods for identifying bed bug populations, each with specific costs, benefits and challenges.
Dogs can be trained to inspect potentially infested areas, seeking out the characteristic scent emitted by bed bugs.
Though using canines can be efficient, there are practical limitations, particularly where air flow and conditions can affect the reliability of detection. Dogs may also sometimes fail to differentiate between active or inactive populations, or the actual location of infestations.
Bed bug monitors have been developed as in-room devices that are designed for detecting bed bugs. More sophisticated monitors use CO, heat and/or kairomones to simulate a sleeping body and attract bed bugs to the device, where glue or pitfall traps catch the insects.
However, consistency of catch, especially at low populations, remains a challenge for these products. Ecolab continues to research the effectiveness of in-room monitors, as part of an integrated pest management program.
Bed bug DNA analysis is a service that can be used to confirm identification of bed bug activity in a suspected area.
While DNA analysis can be bed bug specific, it cannot distinguish between an active population or previous infestation. In addition, only samples that contain insect parts, cast skins or faecal material will be positively identified as bed bug material.
Samples producing a negative result do not necessarily indicate a bed bug-free area.
This continues to be the most practical and cost-effective way to detect bed bug activity.
With adequate education, staff or property owners are the most effective line of defence against bed bugs; as part of their daily room servicing they are well placed to spot bed bug activity.
However, when bed bug activity is suspected or identified, a trained professional pest controller must be called in immediately to provide recommendations on treating the infestation.
Bed bugs like to hide in small cracks and crevices and can easily migrate through wall and ceiling joints from one room to another. Additionally, cleaning and equipment can be ‘carriers’ between infested and non-infested rooms.
All adjacent rooms – including above, below and to the sides – should be inspected, in addition to the infested room. Industry research has reported there is a 20% chance of an adjacent room being infested.
Due to the biology and behaviour of bed bugs, a range of control measures and multiple treatments, with mixed modes of action, is essential to control active infestations.
A direct treatment application to the bed bug is ideal. However, bed bug adults and eggs are often located in areas that are difficult to reach with either chemical or non-chemical control measures. Multiple treatments will increase the likelihood that bed bugs will contact a treated surface and obtain a lethal dose.
Some treatments provide limited residual control and thus a secondary treatment may be needed seven to ten days after the initial application to directly target any newly emerged nymphs.
Furthermore, with some bed bug populations resistant to some treatments, multiple treatments using a range of control actions offer the best chance to achieve total population control and minimise the risk of developing resistance to any one option.
Follow-up treatments also offer the opportunity for ongoing monitoring of activity and the chance to pick up population spread into other areas.
Ecolab research has shown programme efficacy can be seriously jeopardised if any critical steps in the treatment are missed in an infested room.
However, a recommended, multi-treatment protocol (Figure 2) is modelled to be the most effective solution for controlling bed bug populations.
The most effective IPM strategy for long-term bed bug control has proven to use a combination of techniques and products. The most appropriate approach in any situation will depend on an assessment of the site and conditions; some of the techniques may not be suitable, or practical in all instances.
In addition to the core treatment of a professionally applied residual insecticide there are a number of options to be considered:
Heat can effectively kill all stages of the bed bug life cycle. But trials have shown it requires temperature of at least 46°C for at least four hours, or over 54°C for a minimum of 30 minutes. In practice, that proves very difficult and costly to achieve in-situ for a whole room and to bring the fixtures and fittings up to temperature. Surrounding areas must also be treated with insecticides first, to kill any bugs migrating from the heat.
Clearing cracks & crevices
The secretive nature of bed bug populations during daylight hours makes crack-and-crevice treatment a vital component of an effective IPM strategy.
Long-lasting residual activity will treat areas where bed bugs are likely to congregate, including bed springs and box frames, as well as crevices along skirting boards, beneath beds and furniture as well as behind bed frames and headboards.
Recent research supports the performance of the residual insecticide Demand CS on bed bugs. In a 2007 study at Purdue University, Indiana, USA, for example, the crack and crevice treatment completely eradicated bed bugs in six of eight apartments and infestations were reduced by 98% in the remaining two apartments.
In 2015, a study in Lipová, Czech Republic, eradicated the bed bugs in four out of five apartments and delivered 99.7% control in the remaining apartment.
Killing bed bugs with high pressure steam is possible for localised areas, but the heat rarely penetrates far enough to achieve complete control. Over wetting of room fixtures and fittings is unpopular and can create other problems. But used for specific areas, alongside crack and crevice treatment, it can be a useful tool.
Using compressed CO to freeze bed bugs is effective in direct contact, but has many of the limitations of steam control. The action of blasting bugs with the gas can displace live insects to quickly recolonise areas. Trials suggest populations can quickly bounce back after treatment. Again, it can only be used in conjunction with residual insecticide treatments.
Physically covering mattresses has been suggested to stop bed bugs harbouring in bedding material, or trapping infestations in the cover. In practice covers are subject to a high failure rate, either from original manufacture or tears and holes in operation. Also a cover only protects one area and does nothing to address populations in other parts of the bed or room, requiring allied residual insecticide treatment.
Another option has been insecticide impregnated fabrics, which may provide localised control but has the same limitations, along with the exposure risk for customers where no pest is present. A good IPM strategy will target pests only where they are causing an issue.
Insecticide treatment is normally the key to a successful bed bug eradication. Crack-and crevice treatments should be targeted where bed bugs are likely to congregate, as directed by the product label. Focus should be on accurate application to bed frames, as well as in crevices along baseboards, beneath beds and furniture as well as behind bed frames and headboards.
So are 'super bugs' really fully resistant to insecticides? There is certainly evidence of resistance to pyrethroids, organophosphates and other commonly used insecticides in bed bugs. Much of this development has been attributed to poor application, low rates of use and low-quality products that have allowed some of the pests to escape control and develop enhanced resistance mechanisms. Low potency consumer products, applied poorly, could exacerbate potential resistance and, if further applications with the same mode of action insecticide are made, the resistant insects will remain uncontrolled and quickly proliferate.
In the field however, despite resistance, trials have shown that thorough treatments with potent pyrethroids such as microencapsulated lambda-cyhalothrin, Demand CS, can still achieve a very useful level of control. But to ensure complete control of the bugs, it is important to use a range of control measures, as outlined above, and other products with different modes of actions, such as insect growth regulators, carbamates and desiccant dusts.
Best practice to minimise the risk of insecticide resistance developing is to use the most effective available chemistry, at the full approved rate and to apply it as accurately as possible to get complete coverage.