If it feels like there are more cockroaches in Cape Town lately, you’re not imagining things.
Scientists say recent heatwaves and prolonged dry conditions in the Western Cape are changing insect behaviour, making some species more visible while others appear to be disappearing.
Climate change affecting cockroach behaviour
According to IOL, Professor Cang Hui, a Stellenbosch University academic and South African Research Chair in Mathematical and Physical Biosciences, said public reports of increased insect activity are consistent with well-known ecological responses to heat.
“As temperatures rise, many species initially become more active and reproduce faster, but only up to a thermal limit. Beyond that, prolonged heat becomes physiologically stressful.” Hui said.
And, unfortunately, cockroaches and fruit flies are among the most heat-tolerant insects.
During heatwaves, cockroaches often move indoors in search of water and cooler shelter, increasing sightings in homes.
Fruit flies also reproduce faster in warm conditions, especially where organic waste breaks down more quickly.
Crickets, by contrast, are more sensitive to extreme heat and drought. While moderate warmth can increase cricket calls, excessive heat reduces activity and reproduction. Dry soils and stressed vegetation also push crickets deeper underground, making them quieter rather than causing them to disappear.
Hui cautioned that short-term changes in insect activity typically reflect immediate weather conditions, rather than permanent population losses.
However, more frequent and intense heatwaves could lead to longer-term shifts, favouring heat-tolerant species and disrupting ecosystems.
These changes come as the Western Cape endures an intense wildfire season, with hot and dry conditions expected to continue into early 2026.
According to the South African Weather Service, the January to March 2026 forecast shows a strong likelihood of above-normal temperatures across much of the province, combined with a low chance of significant rainfall in the west.
Scientists say insects may be offering one of the clearest everyday signs of how rising temperatures are already reshaping life in the Western Cape.
