Cicada Killer Wasp

very busy flying around the grass, not aggressive even though has a sharp stinger and there are lots of them you can walk right through them and they don't bother you; maybe 3.5 cm long, the head and thorax are solid rust color, the large abdomen is black with yellow spots, you can see through the rust colored wings, legs are yellow, this is female cause it has stinger & males don't