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Black Widow Spiders

9-29-14 northern black widow spiderBlack widow spiders have been found in every state. They are a lot less numerous in New England than further south — their abundance is inversely related to the latitude — however, the northern black widow, Latrodectus mactans, (pictured) is here. According to Dr. William Spear, a noted arachnologist and provider of the information in this post, a black widow in northern New England would need a very sheltered site, such as the south-facing walls of buildings, south-facing sides of ditches, or perhaps even in barns and sheds, in order to survive.

The web of the northern black widow is a rather small (for the size of the spider) messy tangle, usually constructed close to the ground. The spider is generally not found on the web, but in a silk-lined pocket to one side and above the web. The silk of widow spider webs is unusually tough, and with experience one can learn to differentiate it from other spiders’ silk just by testing the web with a stick or pencil.

If knowing that black widows cohabit your state causes some discomfort, rest assured. Their bites are very rare and almost never fatal. The few fatalities that have been recorded are generally from children or persons weighing less than 100 pounds, or with precarious health. (Photo taken by Evan Kay in North Pomfret, Vermont in September, 2014; submitted by Caroline Robbins)

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16 responses

  1. This is a pretty cool looking spider, I’m kind of surprised at it’s attractive pattern, it’s not a solid “RED” hour glass like I thought they should look like! It’s background is also interesting, was this found and photographed as is, in someones car or something? Those look like car seats! Nice shot! 🙂

    October 1, 2014 at 1:14 pm

    • Red hourglass is on bottom of cephalothorax!

      October 1, 2014 at 1:30 pm

      • Thanks Mary! 🙂

        October 7, 2014 at 12:16 pm

  2. Penny March

    This is a male? No venom? Munched after mating?

    October 1, 2014 at 1:16 pm

    • Yes, Penny, this is a male, but it does have venom (his poison glands aren’t as big as a female’s but he has them)! They really are misnomered, as it’s very rare for a female to kill her mate.

      October 1, 2014 at 2:39 pm

  3. Pat

    Whoa! I had no idea they were in New England. Glad to hear they are not usually fatal.

    October 1, 2014 at 1:43 pm

  4. Kathie Fiveash

    I’ve heard that when using an outhouse, it is wise to look beneath the seat to check for black widow spiders. In the “old days” outhouses were often the places bites occurred. The spiders like outhouses because they attract flies.

    October 1, 2014 at 3:39 pm

  5. Nice shot. I was pretty sure L.mactans was the Southern Black Widow and L. variolus is the Northern. Correct?
    Also, in reading the comments above, how do you know this is a male? I was thinking female due to size and clarity of markings on the abdomen, but without a size reference it’s hard to say. Thanks for posting. Joe

    October 1, 2014 at 4:39 pm

    • Most of what I’ve read agrees with your genus and species/common names, but I questioned Dr. Spear on this and he assured me I had it right in the post. Here is what he had to say on gender i.d.: “I get lots of pictures from people who think they have found a black widow spider. Most of them are of other species, but in this case the specimen is clearly a juvenile male of Latrodectus mactans, the northern black widow (something of a misnomer since it is found all over North America). The color pattern you see is characteristic of juveniles of both sexes, but in L. mactans is retained by the males through maturity. The females become entirely glossy black but for the famous red hourglass mark on the underside of the abdomen, and rarely a small red spot just above the spinnnerets.

      October 1, 2014 at 5:14 pm

      • Al Stoops

        I Googled Latrodectus mactans. Several sites refer to it as the “Southern Black Widow. I don’t find any calling it the “Northern Black Widow”, but I do find a few sites using that common name for Latrodectus variolus. Perhaps nhtracking is correct–maybe want to double-check with Dr. Spear?

        October 1, 2014 at 5:46 pm

      • Dr. Spear is of the opinion that common names are basically useless – as long as you have the scientific name of a species, you are certain of its identity!

        October 2, 2014 at 1:00 am

    • Dr. Spear is of the opinion that common names are basically useless – as long as you have the scientific name of a species, you are certain of its identity!

      October 2, 2014 at 1:00 am

  6. Marian Boudreault

    Good timing Mary, I think I have one in my cupboard (under it) will check it out soon with a flashlight and mirror. I had many when I lived in CA. and know the web…very strong and stretchy. I would find them under my deck and in the woodpile every time I went to get wood….sad to say I killed my share as I had young children who ran rampant through the same area they were in. Not sure what to do with this one….Want It ???? Halloween is coming !!!!

    October 1, 2014 at 11:14 pm

  7. Glad to say I’ve never seen one of these, but that doesn’t mean they are not around! Thanks for posting!

    October 2, 2014 at 10:10 pm

  8. Julie

    Wow, what a great picture! The color and pattern on the spider’s abdomen is amazing. I have to say though, that it is definitely a female. I have always lived in desert areas and have had to live with black widows my whole life. The female’s abdomen is more rounded than a male’s, in fact the male’s abdomen is sort of narrow. It doesn’t get as round as the spider you have pictured. It is definitely a juvenile. You can tell by the color on the legs and abdomen. An older black widow will begin to turn a reddish brown and then completely black other than the hour glass on the under side of the abdomen. The hour glass starts out a cream color, then tends to change to orange, then red as the spider matures. Great site you have here. I will definitely be checking out the other pages.

    October 8, 2014 at 6:27 pm

    • Hi Julie,
      Before I published the blog post on black widows, I sent the photograph to Dr. William Shear, a noted arachnologist who has published books about spiders, spent his life studying and teaching about them,etc. and he identified it as a male…I am no spider expert, but he is! Thanks for your interest!

      October 8, 2014 at 6:50 pm

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