moms at work

For the past week or so, I’ve been meaning to write a couple of posts about spiders at the farm, but somehow it didn’t happen. Today is the day.

Since early June, I’ve been encountering female spiders guarding eggs cases. These are just a few of the spiders that I’ve seen (click on all photos for larger views).

I wish I could tell you the species of each of these spiders, but I’m just certain of a couple. The one in the top photo is a Xysticus crab spider found on the underside of a milkweed leaf. Unfortunately, I’m not sure just which species she might be. As some of you may remember, last year, I photographed a similar spider guarding an egg case. It’s possible that this one is the same species. Last year, I guessed that the spider on the case was a Xysticus emerteroni, and after reading the chapter on that species in Douglass Morse’s Predator Upon A Flower, I think that might be the correct ID. He writes that “Of these Xysticus species, only X. emertoni regularly occupies flowers frequented by Misumena.” He is writing about study plots in Maine, but I believe the species we would see here in Ontario would be much the same. Anyhow, last year’s spider was certainly cohabiting in a place where I would espect to see Misumena — the rugosa rose bushes that grow alongside my house. However, the above spider does seem a little different — to my eye, she looked considerably smaller (Xysticus emertoni is supposed to be quite large), and she had very distinct white and dark brown markings toward the rear of her carapace (see above image). I’ll continue to work on an ID for her.

The next spider was a very lovely crab spider which was also found guarding an egg case on the underside of a milkweed leaf. I can’t say I’ve ever seen one quite like her before. She has pinkish markings, with a couple of distinct darker markings along the sides of the abdomen. As in the case of the above Xysticus, she was quite determined to stay put and guard her egg case. I’ll be working on her ID as well.

The above spider was a new one for me — and I believe she might be a Theridion impressum — which is one of the Cobweb Weaver family (Theridiidae). She was very tiny but colourful. I found her among the smaller, central leaves of a milkweed plant. She stayed close to her spherical egg case, clinging to it with her hind pairs of legs.

The last spider was also found on the tip of a milkweed leaf a couple of days ago (please note how *IMPORTANT* milkweed is to all of these species of spiders!!). She’s an Oblong Running Crab Spider (Tibellus oblongus). I find these around the farm quite regularly throughout summer. They are extremely shy spiders, but the females will hang tough and stick with their egg cases even though they may feel threatened. I think this one might have just completed the webbing on the leaf, but not yet deposited eggs as the webbing looks thin and the spider’s abdomen looks larger than it probably would after ovipositing. What I find of particular interest is that I’ve photographed this species with egg cases right around this date in previous years. On June 30, 2004, I photographed this spider reaching out to shelter her egg case (note her slim abdomen). On July 6, 2006, I shot a couple of photos of one of these spiders clinging to a leaf to guard her nest. And on July 1, 2006, I photographed this gravid-looking female. It would be interesting to know if this species has a peak time for laying eggs. If so, the last few days of June and first few of July may be *it* for this region.

If you’re interested in egg-guarding behaviour of another species of spider, be sure to check out Wayne’s recent posts and photos of Pisaurina mira, one of what is known as the Nursery Web spiders, at Niches. Here is the first part, and here is the follow-up to the story.

NOTICE!! I’ve just this moment volunteered to host the June edition of Circus of the Spineless – the invertebrate blog carnival. I realize this is very short notice, but if you have an invertebrate post that you would like to have included, please forward links to me by the evening of June 30th. I hope to get the carnival posted on either July 1st or 2nd — so get busy sending in your links now!

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8 Responses to “moms at work”

  1. jessie Says:

    That crab spider has the prettiest web.

  2. Cathy Says:

    I instinctively looked for a violin marking on that second spider and then I relaxed. I don’t know why, but some spiders just look so much more – well . . . spidery and brown reclusey.

    Honestly though, Bev – I think following along with your beautiful pictures and commentary about insects – I am becomig less fearful and actually look forward to new encounters. But no surprises – please. I shouldn’t wake up with a wood spider on the pillow next to me.

    That maternalism exhibited by spiders is remarkable – even touching.

    Now I’ve got to learn how to pronounce ‘Xysticus’. Sure wish I’d paid attention in Latin class back in the early ’60’s.

  3. Laura Says:

    Would you be so kind as to remind me what magnification these photos are? So I can sleep tonight? They all seem very large!


    I find very tiny spiders around here. The black and yellow argiope that I came across last summer seemed very big, but hardly compares to the sizes in your pics. It’s nice to be able to see so many details in your pics – even if the pics make me squirm a bit.

  4. bev Says:

    jessie – So many of the spider webs are beautiful when you get a chance to examine them up close.

    Cathy – It’s very true that certain spiders seem to strike us differently than others. I don’t mind spiders being around me, but I always feel a slight twinge of something…not fear…but something… at the sight of any of the spiders that look a bit like Black Widows. The funny thing is, I can’t figure out why that should be as I’ve only recently encountered Widows while traveling out west. This seems more an instinctive reaction. I’m glad that you find that the photos of insects and spiders are making you less fearful of them (and not the other way around). I think that it’s helpful to know that all of these small creatures are just doing their thing, living their lives, and that they aren’t particularly interested in the “giants” who barge around stepping on them, tearing down their nests, and spraying them with pesticides. (-:
    As you might guess, I’m fascinated by the egg-guarding behaviour of female spiders. The more time I spend in the field observing spiders, the more I realize that there’s a whole lot that we probably don’t know about the social lives of insects and spiders.
    And yes, all of these scientific names. I never studied latin (I studied Greek though!) so I just stumble along making up my own pronunciations — which I’m quite sure would be laughable to just about anyone. That’s okay though.. I was at a biology conference as few years ago, and met some very charming fellows from the deep south, and their pronunciation of some species had me entirely stymied — it was like I was hearing a different language. Those from France that I’ve heard speaking at conferences have yet another way of pronouncing species names, so I’m gradually feeling more comfortable about just going with whatever pronunciation I reckon sounds okay. (-:

    Laura – Good question! I’ll bet the images in the photos are at least 100x the actual size of these spiders. I’ve read something somewhere about how people remember and describe spiders as far larger than they usually are — compared to how they would remember and describe other creatures such as snakes. I suspect the same goes for hornets, wasps and bees though. My Pbase galleries on hornets and wasps gets far more looks per day than any of my other galleries, especially spring through fall. I get tons of questions from people trying to describe insects that they say are coming around and frightening them, and most describe them as being hornets, bees or wasps that are 2 to 3 inches long. There are so few insects that approach that size that I sure most of them are visualizing and describing things far larger than what they saw. It’s a bit like reading fish tales about how large a fish someone caught! (-:

  5. Pamela Says:

    Bev, beautiful as always–I especially like the first mother–so very serious looking.

    What I have come to love about spiders over the last couple of years is that one can get to know some of them–a goldenrod crab guarding eggs on the rose by the front door will be there for many days (all being well), the orb weavers on the porch ceiling will be there all season. It makes me appreciate spider personality to be able to observe individuals over time.

    And milkweed! Finally, I am learning to really look at what’s on the milkweed, thanks to you. Last week on a day I was chained to my desk almost all day I saw your message to the naturelist about critters on milkweed. I escaped briefly that afternoon and went to take a look and found the very beautiful jumping spider you mentioned, the aptly named, Brilliant Jumping Spider. What a treat!

  6. bev Says:

    Pamela – Those Xysticus spiders *do* take their egg case guarding very seriously. Any time that I find one, it is wrapped over the egg case as though clutching a pillow.
    I agree very much with your comment that spiders give us a chance to observe them as individuals. If you visit enough of them, you even notice differences in behaviour between individuals within a species. For example, some jumping spiders that set up a little territory on the top leaves of a milkweed plant will hang tough when you approach them, but others will freak out and drop to a lower leaf or the ground as soon as you walk near. I visit enough milkweed plants to know which ones have brave spiders, and which have the meek ones that will practically jump at their own shadows. That said, the females of so many species do impress me with their determination to guard their egg cases.
    Glad you got out to do some looking around on milkweed. Over the years, I’ve found that there’s so much happening in even a small stand, that it could keep one busy observing insect communities for most of the summer.

  7. Laura Says:

    Your reply makes me laugh, Bev! I think the same *larger than life* principle must also apply to birds. I do volunteer transport of birds for a raptor rehab and I can’t tell you how many juv. woodpeckers have been described to me as huge hawks or baby eagles! I find that I’m always surprised with how much smaller birds are in the hand, compared with how they look through bins. It seems though that people who don’t *know* birds imagine them to be much larger than they really are. Guess the same is true with bugs and spiders.

  8. bev Says:

    Laura – That’s funny about the birds! But yes, isn’t it surprising how small a bird is when you actually touch it? In early 2005, I moved a road-killed Great Gray Owl off of a highway and was astounded at how little there was to it other than feathers. Anyhow, the tendency to remember things as larger than they actually were is all the more reason to bring a small ruler along in your field note book for measuring creatures and recording that data. I don’t always remember to do that, but when I don’t have one along, I always try to remember to shoot a photo or two with a coin, my finger, or something else in the picture for comparison.