Wasps such as yellowjackets and paper wasps seen at this time of the year are overwintering queens produced by colonies last fall. In the autumn they find refuge in protected sites in and around the home and landscape. The wasps that survive the winter are the fertilized "foundress" queens that will start "from scratch" to build a new nest and colony.
Old queen and worker wasps died last year with the onset of cold weather. The old colony does not persist through the winter and the old paper nest is not reused by the new queens, though they may make the new nest nearby. There is no need for controls at old nests found at this time.
Finding wasps indoors in the spring does not automatically mean there was a nest in the home last year nor does it mean they will nest in the home this year. The only necessary control at this time is to remove and discard the wasps as they are encountered. That should be easy as the queens are generally sluggish and easy to capture or swat.
New wasp nests are best controlled in June. At that time nests are small and easily controlled with the "wasp hornet" aerosol sprays for aerial colonies of paper wasps and hornets or insecticide dust for ground or wall nesting species such as yellowjackets.
(Adapted from University of Minnesota Extension Service "Plant Pest Newsletter.")
This article originally appeared in the April 29, 1992 issue, p. 66.