Noted consumer advocate Clark Howard recently declared Chicago the number 1 rat infested city in North America. If you have been downtown at night you may have seen them on the sidewalks or crossing the street. They really are everywhere.
I know, that sounds like an episode of Monk. But in pest control vernacular, occasional invader refers to pests that show up once in a while; usually because of environmental conditions or other disturbances. Think of earwigs, lady bugs, crickets,