Spring and fall are the mating seasons for scorpions, at which point they may be more frequently seen. The bark scorpion, which has been spotted the most as of late, is considered life threatening, although reports of stings far outweigh fatalities. While this species is native to Arizona, California and New Mexico, the FDA notes that their numbers have been increasing in Clark County, Nevada. Bark scorpions most often grow to be a little more than an inch long, but can grow to over three inches. To discover whether or not there is an infestation, the Arizona-Sonoma Desert Museum suggests waiting until nightfall and shining a black light into dark spaces and across floors and ceilings. Under a black light, their exoskeletons will have a distinct glow.