Please click the link here for symptoms.
Black Widows, as with so many venomous insects, arachnoids and snakes, use their venom to capture prey and eat. So they really don't want to use that venom unless they have to. Often they will inject enough to create a warning. In documented cases where the spider was trapped, say in a sock, you will find they bite several times. The third time releasing all the venom in desperation as they are getting squashed. So the severity varies greatly in an actual bite situation.
The other question often asked is, "was it really a Black Widow?" The classic Widow is shown in the photo, however, there is documentation and identified cousins, that have similar venom that are not the classic color and look, see link.
Black Widows are one of the most aggressive spiders I have encountered in the field and strongly recommend controlling. They will be the most protective around their egg sacks and the larger the spider the more mature, which means they probably do have egg sacks to protect.
Amazingly, as serious as this spider is, and as common, few people actually get bitten. Which proves they are really not "out to get us". They prefer to not be in the same area as humans and usually are under shop benches, sprinkler boxes and to the left and right of our garage doors, where humans seldom frequent. With this in mind, it is wise to teach children, and keep fore most in our own minds, that when we are in a area, that does not have much human interaction, is when we should be the most alert and looking for this spider.
