In recent weeks, residents of houses with gardens in Hungarian cities, especially in the capital, have reported on several forums that they are encountering more cockroaches inside their homes. Fortunately, these are 'only' forest cockroaches and not the German cockroaches that can spread diseases. According to an expert from the HUN-REN Centre for Ecological Research, there is no need for measures like those taken against mosquitoes, as these cockroaches are harmless and will die within a few days indoors.
At first glance, certain species of forest cockroaches can easily be mistaken for the German cockroach, but if we take a closer look, we can spot two small parallel stripes on the thorax of the German cockroach, which can spread diseases and thrives on kitchen scraps. These stripes are absent on forest cockroaches. However, this is not the only difference between forest cockroaches and the ones more commonly found in homes. Forest cockroaches are good fliers and enjoy flying, whereas German and American cockroaches mostly crawl, can only fly short distances, and tend to drop rather than fly. Additionally, forest cockroaches prefer natural habitats over their urban counterparts.
"The suburban forest cockroach (Ectobius vittiventris), one of the most common non-native species, can be found from Italy to the Balkans, through Turkey to the Caucasus, and was first detected in Hungary in 2005, mainly in garden and park habitats around the capital," said Dávid Korányi, a researcher at the HUN-REN Centre for Ecological Research. Since this is a Mediterranean species, the warming microclimate makes it easier for their populations to survive and overwinter. However, cargo transport also plays a key role in the spread of the species, as many non-native arthropods have been detected in nurseries and various shipments.
Forest cockroaches prefer to lay their egg cases in the leaf litter, where it takes about two years for them to reach the adult stage, which can be seen from June throughout the summer. Their peak flight season is in late August and September, after which their numbers rapidly decrease. They primarily seek cooler, more humid places, which is likely the main reason why they seek refuge in the cooler, gardened residential areas of larger cities during warmer and drier periods.
The forest cockroach, besides being harmless to us—it doesn’t spread diseases or feed on kitchen scraps—also dies within 1-2 days indoors. It has many natural predators, including rodents, predatory arthropods, lizards, and even frogs. The use of chemical insecticides is not recommended, even for mosquitoes, as many other insects fall victim to these chemicals. For forest cockroaches, using insect screens and avoiding airing out rooms in the evening with the lights on, which attracts them, is more than sufficient.
Due to the warming climate and increased cargo transport, the heat island effect of cities can become an important hotspot for forest cockroaches, but even so, we don't need to protect ourselves from them in the same way we do against mosquitoes. "These animals are not parasites, they don't bite, they don't spread diseases, and they don't cause allergic reactions, so there's no need for any chemical pest control," added Dávid Korányi.