Early summer weather conditions could lead to surge in wasp populations, warns researcher
The warm and dry weather in the early summer has been ideal for the growth of wasp colonies, according to researcher Jouni Sorvari. He notes that the population cycles of two common wasp species, the garden and German wasp, exhibit significant fluctuations. They appear in abundance in Finland every other year, specifically in even-numbered years. The cause of this phenomenon is unknown but Sorvari suggests it could be due to an increase in diseases or parasites following a year of high wasp activity which then causes a population crash.
Another factor could be the internal competition for nesting sites within the species. If there were many nests in the previous year, there will be numerous queens competing for limited nesting sites in the spring. As a result, many queens die off, causing a further decline in the population.
Sorvari says it’s too early to tell if this year will see an unusually high number of wasps. The garden and German wasp colonies are particularly large in the late summer and they build large nests. At this point, it’s usually noticeable that there are a lot of wasps.
Wasp activity peaks in spring when queens are searching for nesting sites, with another significant increase beginning in mid-July. At this time, there can be a large number of wasps invading people’s dining tables uninvited. According to Sorvari, this behavior is due to a shortage of insect food or insufficient flowering plants for nectar in the late summer.
The garden and German wasp populations continue to grow as long as food is available, but they start to decline in southern Finland by mid-September. Sorvari advises people to remain calm around wasps and live peacefully alongside them. He explains that wasps play a crucial role in nature as predators of other insects. Despite not typically being considered as pollinators, the hairy male wasps can be important pollinators for certain plants.