In Portugal, cockroaches grow mainly in urban areas. The most common species are three:

– American Cockroach (Periplaneta americana)
– German Cockroach (Blatella germanica)
– Oriental Cockroach (Blatta Orientalis).

Cockroaches are active mainly at night when they leave their shelters in search of food.
They have very varied feeding habits, preferring food that contains starch, sugar or fatty foods. They may also feed on cellulose such as papers, excrement, blood, dead insects, rubbish or sewage waste.

They have the habit of regurgitating some partially digested food and depositing faeces while feeding. They prefer warm, moist places.

The sewer cockroach (periplaneta americana) usually inhabits places with a lot of grease and organic matter in abundance such as sewage galleries, drains, grease traps and manholes, service areas, basements, attics, ceilings and also in external areas with a lot of organic matter (rubbish). They are excellent fliers.

The German cockroach mainly inhabits kitchens, pantries, cupboards, drawers, light switches, electrical appliances, lives inside doorways, skirting boards, under sinks and in places such as garages, attics with paper deposits and cardboard boxes, among others. They spend 75% of their time sheltering in the vicinity of foodstuffs. Cockroach infestations are identified by signs such as faeces, skeletons or shells of nymphs that turn into adults. In high infestations, cockroaches are observed during the day and there is a characteristic odour.

Life cycle
Cockroaches lay their eggs in a capsule called an ootheca. This ootheca can be carried by the female to the area close to the hatching of the eggs (Blatella germanica), or deposited in an appropriate place, usually in cracks, crevices, drawers or behind furniture (Periplaneta americana).
Each egg will give rise to a nymph, which, through various changes, will give rise to the adult insect. The nymphs are smaller than the adults, have no wings and are sexually immature.

Blattella germanica (German Cockroach)
Size – 1 to 2 cm.
Habitat – warm places and high humidity
Diet – omnivorous

Periplaneta americana (American Cockroach)
Size – 3 to 4,5 cm.
Habitat – warm, humid and dark places
Feeding – omnivorous

Blatta orientalis (Oriental Cockroach)
Size – 2 to 3,5 cm.
Habitat – cool and humid places
Feeding – omnivorous

Health risks
Domestic cockroaches are responsible for the transmission of various diseases, mainly gastroenteritis, carrying various pathogens through their body, legs and excrements in the places they pass through (they are therefore considered mechanical vectors). They are also vectors of pathogenic bacteria, fungi, viruses and protozoa, causing various diseases (conjunctivitis, digestive tract infections, urinary tract infections, gas gangrene, wound infections, pneumonia, allergies, mycosis, amoebiasis, giardiasis, polio, hepatitis, among others). Cockroach excretions are also frequent causes of damage to computer equipment, such as external disks, for example.

 Importance of Cockroach Control

– The presence of cockroaches causes embarrassment, unnecessary confusion and psychological changes in many people (Catsaridophobia);

– Cockroaches, or parts of their body, when found in food sold to the public, can cause irreparable damage by inducing extremely negative publicity associated with poor hygiene;

– Food contaminated by cockroaches must be prohibited for consumption as, even after being cooked, it may retain the characteristic odour of cockroaches and retain some of the pathogenic elements they carry.

Practices to be adopted for the physical control of cockroaches by a pest control company

– Identification of the species.
Correct species identification provides access to technical and scientific information.

– Understanding the biology and behaviour of the pest.
After identification, the biological and behavioural aspects of the insect can be analysed, looking for information about food, thermal needs, humidity, habitat and aspects of reproduction.

– Determining the level of infestation for the adoption or not of chemical control.
Analysing and determining which local conditions are conducive to the development of infestation.

– Knowledge and evaluation of control measures and their use (risks, benefits, effectiveness).
Evaluate the legally prescribed control methods (products duly authorised by the Directorate-General for Health and/or the Directorate-General for Food and Veterinary Office) available and their application in the situation in question. Consider measures such as mechanical removal (aspiration), trapping, detectors, biological control and others.

– Implementation of safe and effective control methods. Assess the impact of the measures to be adopted on the environment (public, animals, residues in food and utensils).

– Periodically evaluate the effectiveness of the treatment plan implemented.
Carry out post-application monitoring of the level of infestation and, if necessary, adopt complementary control measures. Monitoring done after a treatment can be used as an indicator of the quality of control.

Curiosities

– A cockroach couple, in the period of 1 year, can generate up to 100 thousand descendants, being that in tropical countries this number is easily surpassed;

– There is no chemical product that can penetrate the ootheca (“pouch” that contains the eggs), which is why the established treatment period should be followed, so that the new individuals born from the eggs can be reached.

– Blatella germanica is the most difficult species to control because it has been living with man for a long time, near its food sources and creating tolerance to various insecticides. Due to its proportions, it is able to sneak through any crevice, its nymphs complete their development in less time, and can generate up to 300 eggs.

– The Periplaneta americana or “sewer cockroach” has an average life span of 2 to 5 years, producing up to 810 eggs.

– For each cockroach that sees the light of day, there are on average 50 hidden ones, as they spend up to 75% of their time sheltered in their hiding places.

– The cockroach can live up to 15 days without water or food and 30 days only with water from evaporation, obtained by straining food.