House Cleaning Spider Inventory

by Carl Strang

Earlier I described my impressions of how three species of house spiders distribute themselves in my home. During a recent round of house cleaning I took a mid-winter inventory of them. I was surprised to find them more widely scattered than I expected. I had thought they would be confined to the more humid bathrooms, but such was not the case. I found none in the upstairs bathroom, but 5 in other upstairs rooms (all Pholcus, the daddy-long-legs spiders). As expected, many more were downstairs, with the greatest concentration (10 Pholcus and 1 Achaearanea) in the downstairs bathroom. Other downstairs rooms held 17 Pholcus and 1 Achaearanea. I didn’t run across any Tegenaria.

During the house cleaning I removed all unoccupied cobwebs, and cleared away the husks of discarded prey. The latter process inevitably disturbed the webs of spiders that had set up near the floor. Their response was clearest in the downstairs bathroom, where a few Pholcus and the 1 Achaearanea were at floor level. After the cleaning, the Pholcus all moved up to the ceiling.

The single Achaearanea stayed near the floor, but moved into a more protected corner created by the door frame.

Only that last spider now is in position to take advantage of the most common winter prey, tiny ants.

I realize that this description probably makes my house seem like a scary place. These all are tiny animals, however, and most are hidden in out-of-the-way corners. As I said, I was surprised to find them in rooms other than bathrooms, when obviously they had been in those places for some time without attracting my attention.

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That Other Spider

by Carl Strang

In a recent post I described the two common spiders I find in my house. Last week in the downstairs bathroom I had a brief visit from the third one I mentioned.

This appears to be Tegenaria domestica, the common house spider, a European species. It is the most mysterious one in my home, and the largest, usually appearing briefly and then vanishing. Such was the case this time. It had been weeks to months since I last saw one. This individual was in place for only a couple hours, then it was gone. These are sheet-web weavers, so it probably found some crevice in which to hide until its next appearance.

House Spiders

by Carl Strang

One of the few bad lessons I learned from my parents in childhood was a fear of spiders, especially big ones. As an adult I defused some of this by examining spiders under the microscope, losing the edge of revulsion through familiarity, and discovering an interesting and even beautiful diversity among them. I have come to tolerate spiders in my home, and over the years have noticed three different kinds.

This is the most abundant species. Recently I finally got around to seeking an identification, and with its elongate body and elegant long legs I believe this is the daddy long-legs spider, Pholcus phalangioides (not to be confused with another arachnid, the harvestman, commonly known as the daddy long-legs). These are small, but not to be underestimated. I once rescued another spider that had fallen into the bathtub and couldn’t get out. (I haven’t seen one of these in a while, and don’t have a photo, but it may have been a common house spider, Tegenaria domestica. They are funnel-web weavers, but the males wander in search of females). I dropped the Tegenaria outside the tub, but it didn’t quite reach the floor. It had fallen into the cobweb snare of a Pholcus. The Tegenaria was much larger and stronger looking, and I figured it would break free quickly and continue on its way. Wrong-o. The Pholcus instantly ran up to the larger Tegenaria and, keeping a safe distance with those long legs, quickly wrapped the Tegenaria in silk and made a killing bite. This took only seconds. I felt remorse, but what a lesson!

The third species makes a cobweb snare similar to that of Pholcus. With its rounded abdomen and marbled markings I believe this is Achaearanea tepidariorum, the American house spider.

Like Pholcus, Achaearanea is tiny but not hard to spot against a pale background. Both of these cobweb makers show up all around the house in the summer, but in autumn they gradually concentrate in the bathrooms, and by mid-winter the only place I notice them is the downstairs bathroom. I have thought this is because of a need for humidity, provided by my showers, and references support the idea. This November has been unusually warm, with rains in the latter part of the month. I still have 2 Pholcus in the upstairs bathroom. Downstairs are 4 Achaearanea and 12 Pholcus. I will be interested in following their careers through the coming dry season.

Incidentally, in addition to keeping these spiders around because I am a softie, I like the fact that they take out ants and other home invaders. The Achaearanea in the above photo was perched above the drained carcasses of many prey, mainly ants but also an impressively large beetle.

Likewise, the Pholcus have been keeping ant numbers within reasonable bounds.

Note that this individual has just shed its exoskeleton, and still is pale. Getting out of that old skin must be quite a job with those long slender legs. All three of these species live only in and around buildings. Putting them outside would be a death sentence. They remind us that we are cave dwellers.

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