Two not so itsy bitsy spiders climbed on our bedroom wall. Generally, this doesn’t bother us at all. We tend to leave these tiny visitors alone as they really do not impact us when found in our home.
The size difference caught my attention and I speculated whether I was looking at an age or sexual difference. To understand, I needed a closer look, so I got the camera and took a few pictures. With the flash and shilck sound of the camera shutter, Eileen sat up startled from a sound sleep. I am lucky to have such a patient wife. Chagrinned, and after taking a few more pictures, I put away the camera and went to bed.
After a good night’s sleep, I worked on identifying the spiders. First, I did an internet search on pale spiders in the house. From the pictures, I narrowed the possibilities to a sac spider. Next, I went to bugguide.net and searched for sac spiders. This led me to two very strong candidates, both listed as long-legged sac spiders, genus Cheiracanthium of which two species reside in my area. Studying and comparing the photographs on bugguide with my photos, I started to lean towards C. mildei, as opposed to C. inclusum. Reading further, I learned that C. midlei is an introduced species that prefers houses while C. inclusum prefers the outdoors. I think I have my spiders identified.
From the clearest of my pictures, I decided that at least the one and probably both were female. Female spiders have thin pedipalps, the short stubby leg-like things protruding from by the jaws. The pedipals of the male are swollen as these are what he uses to insert the sperm into the female. A good look at a spiders face can help one sex the spider.
Wanting to know more, I check out bugguides information page and learn that this spider has multiple common names—yellow sac spider and black-footed spider.
I also learn that this spider can be aggressive and bite if trapped in clothing. The spider is listed as “of medical concern” currently, but scientists advocate this classification be removed. A study in 2006 by Richard S. Vetter, et. al. found that verifiable spider bites by spiders in this genus caused some pain and itching, but did not cause any skin lesions or severe allergic reactions. They pointed out that most bites happen while people sleep or as they put on clothes.
Should we worry? No. The incidents are so rare, why fret.
The spiders spend the days hidden in little white silken cases, which we occasionally notice along the edge of the wall or ceiling. Our white walls mean these refuges are well camouflaged. At night, the spiders come out and hunt insects. This explains why I see them when I am ready to go to bed. These spiders do not build large webs, so they do not create issues with ugly webs in the house. Since they help rid our house of bugs and are harmless, we choose to let them stay. If we do decide we do not want them anymore, they get moved outside.
I also learned that I need to take a picture of spiders from the front so I can clearly see the pattern of the eyes, the shape of the jaws and the condition of the pedipalps. These clues help narrow down the identification better than sorting through a ton of pictures on the web.
So, I found another long-legged sac spider wandering around the house and took its picture.
Check out the eye pattern and the pedipalps. With the information provided earlier, can you tell if it is a male or female?
By the way, did any of you sing-song the first two lines of this blog?