They can make me jump but mostly I leave them around the house as they deal with other pests. The large ones we get here are not dangerous. There are some in this country that can bite but I tend to avoid holding them anyway. The furthest I go is to touch one of the large ones on the leg to coax it away from danger; If I am putting the lid back on the water butt, for instance, to avoid trapping it. Probably a 1/10 for me.