A mass depopulation of cockroaches has been observed since the beginning of the 21st century in Russia and other countries of the former USSR. Observers have noted a quick disappearance of various types of cockroaches from cities and towns in Russia, Azerbaijan, Kazakhstan, Ukraine, Moldova, and Belarus.
The depopulation of cockroaches may be exaggerated, or this phenomenon may be temporary or cyclic. A number of explanations of the phenomenon are discussed in the media, of varying degree of credibility.
Usage of plastic bags to store domestic waste and the discontinuation of rubbish chutes usage.
Cockroaches may have migrated out of homes to other, more suitable places.
New, improved chemicals and methods to fight cockroaches may have led to migration, or direct depopulation.
Usage of modern construction materials may also contribute to the phenomenon; the population of cockroaches might have been reduced due to their purported ingestion of unsafe substances. However, cockroaches were noticed to disappear even in the houses where such construction materials were not used.
The emergence of Pharaoh ants, who compete with the cockroaches for food, and may even feed on them.
The introduction of genetically modified food might have a negative influence on cockroaches.
Radioactive or chemical pollution (in Chernovtsy, Tambov, as well as due to Chernobyl disaster) may also be a factor, although there is an opinion that cockroaches are insensitive to radiation.
Widespread introduction of mobile phones and wireless networks might have a negative effect on the cockroaches.
Ozone holes may also lead to abnormal biorhythms in cockroaches.
Internal competitions between cockroaches may decrease the number of cockroaches.
Scientists from Chelyabinsk and Yekaterinburg have suggested that the Oriental cockroach should be added to the Red Book of Endangered Species.
