Beginning in late summer and lasting until early winter, exploring the woods and woodland edges around White Rock Lake demands a certain sense of awareness and keen observation well beyond the norm. Why? Imagine a spider’s web anchored by a line up to 15 feet/five meters long, an orb more than two feet/60 centimeters wide, and a rather large arachnid hanging head-down in the middle. Now imagine having such webs clustered together where every few feet another spider hangs, each one staggered horizontally and vertically in a way that creates an obstacle course made from silk. That describes the peak season of barn spiders (Neoscona crucifera).
In some places, up to half a dozen of these creatures can occupy an area of about ten paces. Some build webs so high that the only sign of them is an anchor line that rises toward the heavens. Others build webs at about face level with anchor lines running some distance away. It’s easy to look at the amount of silk and the length of the anchors with a feeling of awe coupled with confusion: how does the spider cover that much distance in order to build such a massive web? No matter how they do it, they certainly do it well.
The more interesting aspect of this species comes from how variable they are. It’s not just polychroism (variations in colors), but it’s also full polymorphism (variations in colors and patterns). Pattern differences often are more subtle than color differences, though running across one that lacks nearly any pattern whatsoever means scratching my head and wondering if I’m looking at another species altogether.
N. crucifera is often confused with the spotted orbweaver (a.k.a. cross spider or redfemured spotted orbweaver; Neoscona domiciliorum). In fact, even I’ve seen barn spiders that were dark enough to be nearly identical to spotted orbweavers save a few minor differences. In such cases, assuming I can’t tell by size (of the web and the spider), all I can do is note that the spider is one of the two. (Barn spiders are larger than spotted orbweavers; the former also builds larger webs than the latter.)
On the other hand, I’ve seen barn spiders that lacked nearly all markings and the usual colors. Again in these cases, I’m left scratching my head and later performing diligent research with hope of putting a name with the face. I often am surprised to discover it’s yet another variation of the same arachnid. (Of special note is that northern populations of Neoscona crucifera can produce a white variation in females.)
By the middle of autumn, a rapid change starts to appear: a change in shape. Once round and plump abdomens full of eggs suddenly become flat and deflated. The spiders take on the impression of ending. Though they can live until the first freeze—and many do—the creation of the egg sac leaves the arachnid a shadow of its former self, an almost weak-looking thing compared to its previous size.
I admit to an abundance of confusion in the guides and resources used for differentiating these two species. Certain diagnostic markers given for one actually match some of the broad variations in the other. The safest way to tell the difference in places where their territories overlap and a specimen matches both species is to use a microscope to look at the female’s genitalia, or to locate and identify the orientation of a very specific indentation on the carapace (this marker is essentially impossible to see in the field except under very specific circumstances and lighting).
Thankfully in my case, all the individuals, though varied, lacked any true resemblance to N. domiciliorum. Then again, were one to take the guidance on colors and patterns as definitive, then several of them didn’t match N. crucifera either. What I’ve seen in researching them is a growing body of evidence which indicates a level of polymorphism similar to cricket frogs.
[all photos are of females]