There are reasons sometimes. I am not arachniphobic, since by definition that is an unreasonable fear, but spiders are killed on sight in my home. Not only is it a bug that has invaded my ( human) space, i seem to have an allergy. A teensy one walked over my cheek while cleaning a storage area at work, something we called a pallet spider as they seemed to love the pallet storage pile. I simply brushed it away, no freak out. The following morning i woke to half my face swollen to the point i could not open my right eye at all. Once the meds reduced the swelling a line of about 8 bites could be seen across the cheek.