Wasp population in Ireland has experienced a huge decline this year possibly due to to last summer's inclement weather, say experts.
“Last year was so wet that wasps did very poorly. Low numbers this year are a carryover as few queens went into hibernation," said Alan Stubbs, from the Buglife Conservation charity. However other reasons may not be known.
“Social wasps, or what I call jampot wasps, normally undergo cycles of good and poor years. We happen to be in an exceptional low year at the moment.”
According to the Irish Examiner, the wasp population depends on queens who establish colonies and lay eggs in underground nests. On average, a nest can contain up to 5,000 wasps at the the end of a summer. Populations can rise to up around 10,000 during very hot summers.
However, a period of hot and then cold springtime weather can be detrimental to the colonies if the queen comes out of hibernation too early only to be hit by a blast of cold weather.
“The queen needs good weather to found a new colony in the spring. Only when the colony has built up strong numbers of workers can it afford to feed larger grubs which become males and new queens," explained Stubbs.
“After mating, only the new queens survive through to the next year. The remaining workers perish when winter sets in as there are hardly any insects to feed on and it is too cold to fly.”