Insect and Spider Identification: CLOSED: Request for bee or wasp ID, 2 by Valgeristik

Valgeristik wrote:
Hi!
I have been trying to identify these little guys for a week now with no luck.
Found in Estonia, Haapsalu (north-eastern europe), inside the house, frequently 2-3 individuals at a time, so I\'m assuming they\'re a social species.
About 1.5 cm in length, makes high-pitched buzzing sound when stuck or distressed or possibly as communication with the others? White stripe on the abdomen. The abdomen is fluffy-ish. The wings are a transparent brown color.
I\'m unsure if they\'re able to sting, I haven\'t seen a stinger. Very non-threatening, so I was able to handle them with bare hands a few times while carrying them outside.
I have looked at scoliid wasps, but none of them fit the look 100% + they are solitary species.
I had never seen them before, and now I\'ve seen about 15 of them in the course of one week, so I\'m wondering if they\'re just rare or an invasive species of some sort.
Thanks in advance!