While not incredibly common, in Michigan there are a couple of species of poisonous spiders. Often, kids grow up "playing" with daddy-longlegs and have heard the frequently told myth that the daddy-longlegs is the most poisonous spider, but their fangs are too small to bite humans. Michigan does have poisonous spiders; however the daddy-longlegs does not qualify.
Northern Black Widow (Latrodectus variolus) Identification
Michigan is home to the northern black widow spider. Shiny and black with a very round abdomen, black widows are very distinct. Including their legs, the female is about 1 1/2 inches long and has a red hourglass-shaped marking on the underside of her abdomen; males are slightly smaller and lack the red spot, but often have red and yellow spots or stripes on the back.
Northern Black Widow Poison Toxicity
Black widows can be found around woodpiles, outhouses, in meter boxes, basements and other solitary spots. The bite tends to be painful and cause a severe reaction. The bite location may swell and hurt around 30 minutes later and further symptoms include muscle cramps, spasms, tummy pain, vomiting or nausea, rising blood pressure, sweating and unconsciousness, perhaps you can even stop breathing. Death can occur--although rare--in the extremely young or old. However, as Discover Magazine notes, black widows can deliver what are called "dry bites" to warn off predators without wasting their venom. Always seek medical help promptly if a widow bite is suspected.
Brown Recluse (Loxosceles reclusa) Identification
While the brown recluse spider is not native to Michigan, and is usually found in the Southern states instead, Michigan DNR notes that there is a documented case of the recluse in Michigan, and other reports suggest that, perhaps due to hiding in shipping crates from the Southern states, the brown recluse exists, although rare, in the Lower Peninsula. Yellowish to brownish in colour, the recluse is about 1/2 inch long with long, delicate, hairy legs. The brown recluse has three pairs of eyes and a violin marking on its back.
Brown Recluse Poison Toxicity
Nocturnal in nature, the recluse prefers solitude. Not aggressive, it will bite only if disturbed. Bites are rarely fatal, and can also be "dry." The recluse packs a lot of venom for its size, and is considered highly toxic, especially to the very young or old. Pain and itching will grow about four to eight hours after bite, with redness and swelling, then a blood blister developing. An ulcer--an open sore where flesh is dying--will begin as the tissue toxin spreads. Fever, nausea and vomiting, joint pain, and even death can occur. Seek medical help promptly if you suspect a brown recluse bite.
There are two different types of daddy-longlegs; one is a spider and one is not. They are now generally referred to as daddy-longlegs and daddy-longlegs spiders.
Daddy-longlegs, also known as granddaddy-longlegs, harvestmen and opilionids (the family they belong to, of the order arachnid) have one body segment instead of two, as true spiders have and are not poisonous. The daddy-longlegs spiders found in Australia and along the Pacific Coast are actually spiders, in the Pholcidae family, but don't spin webs and are also not poisonous at all, as far as current research indicates as of 2010.