In the fifth in a series of articles looking at the effects of the changes in human behaviour caused by the Covid-19 restrictions on pest species populations and behaviour, we look at the common species of cockroach. At the tail end of March 2020, the UK was plunged into conditions none of us have seen in our lifetime.
Governments around the world have limited the movement of citizens and closed non-essential businesses to the public with the goal of minimising the spread of the Covid 19 and now that we are in the grips of second national lockdown, we can see how well cockroaches fair with a protracted change in fortunes.
We have a number of cockroach species in the UK but really only 2 would be considered common, the oriental and the German cockroach.
Cockroaches
The oriental cockroach is found in high-temperature areas such as kitchens, laundry rooms and hospitals. They are dark brown to black in colour. Females have a length of 1 to 1-1/2 inches and just rudimentary undeveloped wings. Males are a little shorter than females and have wings that do not reach to the end of the abdomen, which are fully developed. Females lay around 8 egg capsules in her lifetime, each having 16 eggs that hatch in about 44 days.
The German cockroach, which is arguably the most widespread in the United Kingdom, is light brown with two dark longitudinal stripes on the thorax. Adults are around 5/8-inch long and have fully formed wings in both sexes. With an average of 32 eggs in the ootheca, these cockroaches are prolific breeders. Typically, harbourages will be warm, dark, and they will have small cracks and crevices to hide. In general, such areas would be very moist or situated near water sources and food supplies.
During the first lockdown, many commercial buildings favoured by both species were left vacant. Even with thorough cleaning it is not really possible to remove all cockroach food sources. They can survive for long periods on just residues in inaccessible areas. Without people in their environment, populations have been allowed to grow unchecked. As a result, we have encountered infestations the like of which we haven’t seen since the invention of insecticidal bait. Populations are far heavier than pre lockdown, but the populations are far less dispersed, concentrated to a few spectacular population centres. We have seen this behaviour in hotels, restaurants, hospitals and care centres. These infestations had been discovered by maintenance staff bringing sites out of moth ball. It will be interesting to see if this behaviour is repeated in the second lockdown.
Cockroaches are one of the oldest insects in evolutionary terms. We know from archaeological evidence that they walked the earth with dinosaurs over 350 million years ago, or 349.5 million years before we evolved from Neanderthals. It is no surprise that cockroaches were not adversely affected by lockdown however I do not believe anyone could have predicted the speed their populations would grow in our absence.
