Whilst brainstorming topics for our deBugged blog recently, I asked my husband whether there was anything he wanted to know about pests: cockroaches specifically. His immediate response was, ‘Is it true that cockroaches only come out at night?’
That’s a relatively easy one to answer: cockroaches do only come out at night, and that’s because – like many other insects – they are nocturnal. The word nocturnal springs from the Latin word ‘nocturnus’ which means ‘of the night’ and has come to mean anything that is active at night.
Circadian Rhythms of Nocturnal Insects
The nocturnal nature of many insects, including cockroaches, scorpions, and mosquitoes is governed by their circadian rhythms. Circadian rhythms are activity cycles that are about 24 hours in length and affect the behaviour of different organisms. Almost all living organisms follow a circadian rhythm. The circadian rhythm of nocturnal insects dictate that they are inactive during the day and to start to hunt for food at night. It is thought that some insects may have evolved to be nocturnal to avoid the heat of the sun and the many diurnal (daytime) predators like birds.
Cockroaches will emerge at night to feed on whatever they can find in your house. Unlike my daughter, they’ll eat just about anything, including food that’s been left out or dropped on the floor, pet food, debris behind the fridge or around the rubbish bin, sludge behind the stove, or any other source of fresh or rotting food matter. That’s why one of the best ways to prevent cockroaches is by keeping your house – but especially your kitchen – clean and free of anything that could act as an attractive food source.
So do they ever come out in the day, I hear you ask? Yes, they do, but if you are seeing cockroaches during the day, it is a good indication that you have a significant infestation. Daytime activity usually means that there are so many cockroaches in their usual hiding places that they are forced to hunt for food at less than ideal times due to overcrowding.
Do Cockroaches Sleep?
A handful of studies have been conducted on the activity cycles of cockroaches, attempting to answer the question of whether cockroaches ‘sleep’. The research suggests that cockroaches do follow a specific circadian rhythm, which includes a resting period or period of inactivity during the day. Maybe it’s not quite the 8 hours of shut-eye that we aim for, but it’s certainly a sustained period of inactivity.
According to Professor Irene Tobler-Borbély, cockroaches have three states of activity: a period of locomotion, a period of limb or antennae movement but no locomotion, and a period of immobility. Under normal light conditions (light by day and dark by night), activity only occurred at night, and most activity occurred during the period just before midnight. There was little activity during the later hours of darkness. The immobility period is similar to what humans would call “sleeping.”
A previous study also suggested that artificial lighting at night could interfere with cockroaches circadian rhythms, thus preventing them from becoming active. In this study, artificial illumination almost entirely prevented the cockroaches from appearing. Even lower intensities of light greatly reduced the number which appeared.
Where do Cockroaches Sleep?
Being nocturnal, cockroaches dislike daylight and thus disappear during the daytime for their resting period. They prefer dark, moist places and will secret themselves just about anywhere that meets these criteria, including the undersides of appliances like stoves and refrigerators, underneath sinks, near plumbing, inside light switches and behind wall panelling. They have been known to hide inside bookcases and furniture, inside the folds of curtains or other fabrics, in piles of old newspapers, paper bags or pet food bags, and amongst brooms or mops. Their hiding places are nearly endless, provided they are dark and mostly undisturbed. Because they can flatten their bodies to fit into narrow areas, cockroaches may also be found hiding beneath rubber mats, behind wallpaper and within wall cracks.
Visit our website for tips from the experts on how you can ensure that you don’t have to share your home with these nocturnal housemates. And if you do have the misfortune to head into the kitchen for a midnight snack, only to find they have beaten you to it, call Rentokil for a free quote.