Another group of ground-nesting wasps is the digger or Scoliid wasps. Scoliid wasps are about 5/8 inch long, blue-black, with blackish purple wings. There are two yellow stripes, one on each side of the abdomen. Their bodies are fairly hairy and the back part of the abdomen is covered with reddish hairs.
In late summer, they can be seen flying or hovering over lawns in large numbers during the heat of the day, leaving in the early evening.
Scoliids are beneficial wasps parasitic on beetle grubs, including Japanese beetles.
They are not aggressive and generally do not attack people. They disappear at the end of the season.
Adults are often seen visiting goldenrod flowers in late summer.
Management is not necessary or recommended.
Scoliid wasp. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
