Bed Bugs
Biology
Bed bugs belong to the family Cimicidae, within the order Hemiptera – the true bugs. There are two common species that feed on humans, namely Cimex lectularius and Cimex hemipterus. Cimex lectularius is the cause of most domestic complaints, and is known as the common bed bug.
Description
Adult bed bugs feeding Adult bed bugs are oval, wingless insects, which are about 5-7 mm long. They are flattened dorsoventrally and this particular feature allows them to hide in narrow spaces such as into cracks and crevices. When unfed, they are pale yellow or brownish in colour, but after a full blood meal, they take a darker uniform ‘mahogany; brown colour.
Bed bugs have piercing mouthparts formed into a proboscis, used to pierce the host’s skin. They have three pairs of legs that are slender but well-developed and with efficient tarsal claws for clinging on to the host during feeding.
Biting Habits
Both male and female bed bugs take blood meals and are thus equally important as pests. Blood provides them with the proteins necessary for their survival and for the production of eggs in females. They normally prefer human hosts to fulfil their blood requirements, but in the absence of people, bed bugs will also feed on a variety of other hosts, such as rabbits, rats, mice, bats, poultry and other birds.
During daylight hours, both adults and nymphs hide in dark and dry places, such as in cracks and crevices commonly found in furniture, walls, ceilings or floorboards, underneath seams of wallpaper and between mattresses and beds. At night, adults and nymphs crawl from these resting places to feed on sleeping people, after which they return to their resting sites to digest the blood meal.
Life Cycle
Females lay their eggs in cracks and crevices. They produce an average of 2-3 eggs per day. During their lifespan that usually extends over a few months, each female could lay on average 400-500 eggs
Cimex lectularius bionomics – Eggs
| Temperature (°C) | Egg hatching time (days) |
| 10 | 22 – 25 |
| 23 | 12 – 14 |
| 27 | 6 – 9 |
The eggs hatch after about 12 – 14 days at 23°C and give rise to nymphs. These newly hatched bed bugs also feed on the blood of vertebrates. Hatching could take place within less than a week if temperatures are about 27°C, and under lowtemperature conditions, it may be delayed for several weeks. The unhatched eggs could remain viable for 3 months.
There are a total of 5 nymphal stages. The developmental time is greatly dependent upon temperature, food availability and relative humidity. Each nymphal instar would require one or more blood meals for further development.
The life cycle from egg to adult can be as short as 3 weeks under ideal conditions. Adults survive more than a year without blood feeding.
Cimex lectularius bionomics – Egg to Adult
| Temperature (°C) | Complete cycle (week) |
| 16 | 34 |
| 20 | 17 |
| 23 | 9 |
| 25 | 6.5 |
Nuisance Pests
Because of their preference for human hosts, bed bugs live in close association with human beings and consequently cause substantial nuisance through their bloodfeeding habits. The bites cause itching and redness for most people.
Medical Importance
There is no evidence of bed bugs being involved in the transmission of infections or diseases to people, and they are therefore not considered to be disease vectors.
Bedbug infestations can however cause considerable distress. Reaction to their bites is variable. Some people show little or no reaction whereas others may suffer severe reactions and have sleepless nights.
Control
Inspection
While attending a bedbug complaint, the first step is to conduct a thorough inspection of the premises to determine the extent and source of infestation. Areas that need to be covered include mattresses, bed frame, bed head, bedside furniture and other furniture, electrical fittings and appliances, underneath carpet edges and skirting, wallpaper and paint if loose, curtains and any wall hangings.
Signs of bedbug infestation include the presence of live bed bugs, cast off nymphal skins, and hatched or unhatched eggs. A bedbug infestation could also be detected by small dark brown or black marks on the bed sheets, caused by the bedbug’s excreta that consist mainly of excess blood ingested during feeding. Houses with large bedbug infestations may have a characteristic sweet and rather sickly smell.
It has been noted that bed bugs are commonly introduced in second-hand furniture and bedding, where the bugs often remain undetected for considerable periods until a suitable host appears. It is thus strongly recommended to get the furniture inspected and/or treated by a pest control professional to eliminate the risks of introducing an infestation indoors.
Bed bugs occasionally crawl from one room to another, spreading the infestation throughout the hotel, hostel, or domestic premises.
Chemical Treatment
Upon identification of a bedbug infestation, a residual spray application (microencapsulated formulation for longer residual) could be carried out on thefloors, walls and furniture.
Additionally, it is recommended to conduct targeted treatment of cracks and crevices, which are the main harbourage areas, with either a residual spray or dust application. These cracks and crevices could be lightly sprayed with a flushing agent to test for the presence of bed bugs.
The suggested treatment regime, shown below, utilises a mixture of insecticide groups and formulations, ensuring an integrative approach to control and resistance management.
