Adults – reddish brown
Wingless, dorsally flattened insects
Adults about 6 mm (size of an apple seed).
Resurgence in populations of bed bugs, Cimex lectularius Linnaeus, has been reported in Australia in recent years. The proliferation of both Cimex lectularius (common bed bug) and the related Cimex hemipterus Fabricus (tropical bed bug) has been attributed to increased travel, the exchange of used bedding and furniture, limited availability of effective and approved insecticides, insecticide resistance, and the cyclical nature of the species.
Bed bugs undergo an incomplete metamorphosis during which they pass through five nymphal instars. Each of these nymphal stages needs to feed on blood before it can moult into the next stage and eventually into the adult reproductive form. Both adult males and females then need to continue to take regular blood meals in order to reproduce.
The total development process from egg to adult can take place in as little as 37 days, though often it might take much longer. The adult bed bugs will typically live for about one year, depending upon temperatures and availability of blood meals.
Bed bugs are cryptic insects. This means they spend most of their life hidden away in cracks and crevices where they will not be seen or disturbed. This lack of activity often prevents bedbugs from coming into contact with fresh insecticide residues applied to mattresses, bed stands, box springs, walls, floors or other surfaces upon which they normally travel.
Typically they will emerge between midnight and five in the morning, when people are in a deep sleep, in search of their blood meal. They will travel over several metres in a random manner in search of a host. They are attracted by heat and carbon dioxide given off by resting people, but usually they need to be within 1 m of the source to detect this.
Bed bugs mate by a technique referred to as traumatic insemination. The male bed bug literally stabs his reproductive organ into the female’s body wall where it penetrates a specialised organ on her right side, known as the Organ of Berlese.
The number of eggs that a female will lay is dependent on the number of blood meals she obtains and the ambient temperature. On average a female bed bug will lay between 1 – 7 eggs a day for up to ten days after each blood meal. Typically she will produce around 110 eggs in her life and these will hatch 50:50 into males and females. This means a bed bug population can double in as little as 16 days in optimal conditions.
Most infestations are focused around where people sleep, but in cases of large infestations they will spread out. There is also a modern trend with infestations occurring in shops, offices, hospitals, physician waiting rooms, and public transport systems.
Once the bed bug finds a host, it probes the skin with its sharp mouthparts seeking a capillary space. They may probe several times to find a suitable blood flow to feed on. Thus people may get several bites from the same bed bug. Typically they feed for around 5 – 10 minutes before leaving to hide away once more in a dark crack or crevice nearby. They usually feed every 3 – 7 days, so most of the time the population is hidden away digesting their previous meal.
Due to the nature of this pest, its increasing prevalence and the traumatic injuries they can cause, they have been the subject of a great deal of research in the past. In Australia it has been well documented that some of our bed bug populations are resistant to the commonly used pyrethroid insecticides, which makes control more challenging.
This has lead to the development of a Bed Bug Code of Practice (LINK: http://medent.usyd.edu.au/bedbug/bedbug_cop.htm). This Code was developed by Dr Stephen Doggett of the Department of Medical Entomology, Institute for Clinical Pathology & Medical Research, at Westmead Hospital; on behalf of the Bed Bug Code of Practice Working Party, established by the Australian Environmental Pest Managers Association.
This document covers all aspects related to the management of bed bugs and should be followed by a professional pest manager when providing a bed bug treatment. The strategies to be followed will depend upon the size and extent of the infestation; and whether it is in the introductory phase, established phase, growth phase or spreading phase. A multi-disciplinary approach is always required and the involvement of the property owner in the process is essential.
Treatment of bed bugs requires a thorough and detailed approach by all parties and a combination of chemical and non-chemical controls, together with hygiene and housekeeping measures.
Article prepared by Steve Broadbent, Ensystex Australasia Pty Ltd on behalf of the Australian Environmental Pest Managers Association. Photographs courtesy of, and copyright of, Dr Stephen Doggett.
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