The cockroach is probably one of the best known and most hated of insects. It is associated by most people as an indicator of filth and unhygienic conditions. The cockroach descends from an ancient lineage of insects which have inhabited our planted for around 100 times longer than humans. Some 4000 species are recognised today, of these only about twelve are commonly associated with humans. Due to their close contact with humans several common names have been given to these insects. The actual name cockroach is reportedly of Spanish origin, derived from the word "Cucaracha". In the UK the Oriental Cockroach Blatta orientalis is referred to as the "black beetle" due to its dark colouration. It is also called the "mill beetle" and the "black clock", probably due to its appearance at dusk in mills. In certain regions of Europe the cockroach has been given local names which infer that the insect originates from a neighbouring country. "Steam-bug" and "Steam-fly" are all local names for the German Cockroach in various regions of the world.
Cockroaches lay their eggs in little purse-shaped containers called "ootheca" and these can often be seen projecting from the female abdomen. Most cockroaches deposit their purses soon after they are formed but B. germanica carries hers around until the eggs are about to hatch. The number of eggs in a purse varies from 12 - 50, with each species having it own range and average. The nymphs are worm-like when they first hatch, but as soon as they reach the air they shed their skins and emerge as tiny cockroaches. Metamorphosis is slight and there are between 5 and 12 moult, according to species. The nymphs take several months to mature.
Adults and nymphs will feed on a variety of organic food, including that intended for human consumption, rubbish and waste in sewers and drains. Both the Oriental and German cockroach are known to carry Salmonella and staphylococcus bacteria so there is risk of contamination from the insects onto food and food surfaces.
As both species of cockroaches do not readily emerge during the daytime and night inspection may be impractical, infestations may be monitored by visual evidence and insect monitors.
In view of the many potential and often inaccessible harbourages available to these insects, effective control of these pests is often very difficult and because of this, the help of a professional pest control officer should sought.
Before any kind of insecticide treatment is carried out, it is essential that the product label is read and is understood.
Read the product label and wear appropriate personal protective equipment. Carry out treatment in accordance with the labels instructions.
Prevention and maintenance
The design of buildings to minimise voids and crevices is important to prevent harbourage for the insects in the first instance. Good hygiene practices, the removal of food debris and thorough cleaning will eliminate the food source. It is good practice to have a regular system insect monitoring in food and health establishments so that infestation can be identified early and dealt with before contamination can occur.