Friday, December 10, 2010

Introducing the Black house spiders

The black house spiders are my favourites. OK, these photos aren't as pretty as the orb weavers, but I really love these guys. I can watch them all the time, because they build their funneled webs all over the house. Webs are not cleaned off, and so they build up as new spiders take over old webs. The back verandah is a lacework of webs with about 70 spiders out there at any one time, 30 or so on the door panes. There are two species, the larger black house and smaller grey house (Badumna insignis and Badumna longinqua, Family Desidae).

In their funneled webs, Badumna longinqua (l), body length about 14 mm, and Badumna insignis (r), with a body length of about 18 mm. The males are about half the size of the females.

I will blog these spiders a lot, because they are my constant companions. Mostly it will be the larger of the two, B. insiginis.

In this post I will just introduce the three individuals who I have chosen to blog. They live on the back door, which consists of 20 panes. The numbers in the names refer to their door panes, numbered, not very originally, from 1 to 20. 99% of spiderlings do not make it to maturity. For 4 years I have been leaving the webs on the door panes, in the hope that one day I will see a female making her egg sac, and then see the young hatch. But the birds usually take the spiders when they get to a good size. Today I finally witnessed an egg sac being made!

Mother-13 was clearly gravid - ready to lay. Her abdomen was quite swollen. This was what I could see through the glass pane yesterday. This is into her retreat, so she has lined it with silk. But at least I can see her.

Mother-13 ready to lay.

Then, this morning I saw it. Mother-13 was spinning her egg sac, which she had attached to the glass. Here she has just finished. You can see how much of her abdomen full of silk has now become egg sac and eggs.

Girl-in-one and Guy-in-one are a male and female in pane one, who have been cohabiting for two weeks now. Most male spiders do not become dinner for their mates - that's just a few species. I am hoping for another egg sac at some time soon. This is how they look to me from inside the kitchen.

The smaller male, Guy-in-one, above, and the female, Girl-in-one, below, are cohabiting. The female would not tolerate another living creature in her web other than a male. She'd eat it.

Upsider is a much more typical black house spider, in that she has her retreat worked into a crevice. In her case, it is into the brickwork next to the door. She always rests upside down. An individual will tend to always rest in a particular orientation, even though the entrance appears to be pretty regular to me. 

If you look closely at the full size (click on the image) then you will see that Upsider's fangs act like pincers - pointing toward each other. That's the way they are in most spiders, often referred to as 'modern' spiders. The 'primitive' spiders - trapdoors, Australian funnelweb spiders and mouse spiders - have their fangs pointing downward. They raise their front half to strike down on prey. I will blog our Victorian trapdoors in another post. Upsider has 8 eyes, in rows along the top of her head (well, bottom of her head, given that she is upside down). The eyes are very small, and mostly detect light. Upsider detects the world through her sense of touch - through air movement over her hairs, and through the web.

You have now met them. They live pretty active lives, as future posts will show.


Regal fed extremely well today. I couldn't identify the shrouded creature, but I would guess it was a large flying beetle.

An hour outside tonight, and I counted 34 orb webs. Most will not make it to full size, but some will. It's going to be a wonderful summer!


  1. I have recently surprised myself and become extremely attached to what I discover from your posts, is a black house spider. She lives in the window of our shower and so every morning while I'm showering I catch up with her and observe her incredible life.
    I read in some posts of yours about this spider, that you had observed some very small individual spiders sharing the web. did you ever find out what these were? I have been assuming that they were the male. I have a few other females living in various parts of the house and they all seem to have a small spider in with them at the moment.

  2. Hi Wolfatron, I am so pleased to have a comment on my new blog! Especially one so interesting. Thank you! I will do a blog tonight on this very topic and copy in your comment. I am very interested that you have also noticed the small spider in the webs. Mine all have them as well, so maybe they are some other species which lives on the leftovers. But I have reason to think that is not the case, because of the timing of their arrival.

    I have another theory as well, and your observations will greatly help me evaluate it. Could it be that the very little ones are the males of Badumna longinqua, the smaller cousin? I have lots of them on the verandah as well. Could it be that the two species can't distinguish the difference, and the females don't mind them because they still behave like males? I know there are other species of the same genus who will attempt to mate, but the genitals don't match, so they don't manage it.

    So my Big Question for you is: Do you also have lots of the smaller webs as well?

    I'll add some more black house news tonight and pose this question. Alan Henderson might offer an opinion on it.

    Thank you again for being my first commenter!

  3. Hi Lynne,
    Since I last posted the above comment some interesting things have happened..We went away over the summer for three weeks and when I got back the web was full of small eggs sacs. This was consistent with the advice I had had from The Melbourne Museum about what to expect if the small spider I discussed in my first post was indeed male. Within a week or two they started hatching, some of them right before my eyes as I showered!! It seemed that many of the spiderlings dissappeared overnight for the next few days, until eventually there was about 100 left. That was at least 3 weeks ago and they are still there. They are just gorgeous. Just like Mum but mini.
    In answer to your question about the other webs in, on and around the house. Our house was covered in similar webs up until 2 weeks ago, even some inside, when my family put their foot down!! I was allowed to keep three, all on the bathroom window. These are actually in very hard to see places unfortunately.
    I have some photos of my spiderlings that I will try to post but my internet connection is playing up!!
    We also have golden orb weavers all over our garden and I have noticed that this year there is a particularly large population of them. We are relocating quite a few of them to a local park as they are making their webs right where we walk at night.
    My fave though? My gorgeous black girl..

  4. Hi wolfatron,

    So good to hear from you! Looking forward to you posting the images. I'll answer most with your other posts on the later blackhouse post. The babies are adorable, aren't they? So good to hear your descriptions. Our spider numbers are way up as well - so are the insects. That's no coincidence. It's wonderful.

    I must do another blog. I have so many photos, but they take time to sort, select and process. We've been flat out because we suddenly decided to move to Castlemaine, and our house sold within a week. My family have asked that I be a little more selective about how much of the new place the spiders can take over. I saw blackhouse and orb weavers there, or we wouldn't have bought it. But no burrowers - yet! My blackhouse here had to be moved off the windows and doors to sell it - the agents thought it would put people off - which broke my heart. I went away for the day while husband and daughter moved them one by one. Damian found that by twisting the web gently on a stick, the spider followed to stay with the web. So did the babies. Then the adult ran up and down the stick while he moved it over to the pergola, where they were carefully deposited with the mass of silk. Fortunately the new owner likes spiders. I'll leave a copy of the book.

    But I have photos of Mother-13 and the babies as they hatch. I finally got to see one right through from a spiderling herself to weaving her egg sac and the young hatching and dispersing.

  5. That's so sad! Life! Good luck at your new home, I hope you find some beautiful spiders there.