Here are some pictures from this year’s megaweb at Arkansas Bend State Park in Lago Vista, Texas. Similar to last year’s web at Lake Ray Hubbard, these webs are primarily constructed through the efforts of thousands of Tetragnatha guatemalensis (common name: Long-jawed Orbweaver). Of course, there are many other species present within the webs! And also, pictures and videos just can’t do it justice, if you can make it out to the park, I highly recommend visiting the webs in person 🙂 Enjoy! Videos to come.
In Texas, it seems that heavy spring rains bring lots (I mean LOTS) of late-summer spiders. For instance, in 2007 a giant spider web popped up at Lake Tawakoni, made from the labor of thousands of Tetragnatha guatemalensis individuals (with possible help from some other species). The running hypothesis for these massive spider outbreaks can be simplified to this: heavy rains cause huge blooms in insect populations, spiders feed on these insect populations, and so, spider populations grow to larger-than-normal sizes. Although orbweavers such as T. guatemalensis do not normally cooperate in web-building (that is, they are not social spiders, per se), they may be more tolerant of others and even share web space when prey populations are large enough (i.e. competition is low). Joe Lapp (or, Spider Joe) carefully documented this outbreak, and you can read more about it (and watch some interesting videos of spider behavior), here on his blog.
I wasn’t living in Texas in 2007, and so have only heard about these occasional massive outbreaks of spiders. Although this is the stuff of most peoples’ nightmares, it is the stuff of an arachnologists’ dreams. So, when I heard that this August (2015), there was another outbreak in Northern Texas, I was very excited to be able to see it, and take a few pictures to share with others. Unfortunately a few days before I could go to the site at Lake Ray Hubbard, officials had sprayed pesticides around the area, in an effort to control mosquito populations. Thus, the webs that I saw were not as pretty and pristine as those shown on the news (see links below), and many of the spiders had died as a result of pesticide exposure. Still I got a few good images and it was really a wonder to see the sheer number of spiders that could all live in one place.
You can read more about the 2015 outbreak (and find some pre-spraying pictures of the webs) by following the links below:
Guess what…. I’m buying a real camera soon! This means that I’ll finally be able to be a real ento-blogger, educating the world about all the cool critters out there 🙂
In the meantime, here are a few pictures I’ve taken over the past year of spiders (and other arachnids) using my current camera (my iPhone). Enjoy!
Sorry for the long wait, but hopefully you all are ready to learn more about spiders! While I haven’t been posting about spiders, I have been learning a TON about them, and have lots of fun things to talk about, now that I know so much more about arachnids.
To start, here are just a few of my favorite spider-related studies that have been published during the last seven months… enjoy!
Spider silk may be ready for commercial production…
Hormiga & Griswold published this great review of the evolution and systematics of orb-weavers – PDF: AnnuRevEntoOrbweaving2014
As did this cart-wheeling spider. 🙂
I’ll be discussing some of these studies further in the near future, as well as talking about an arachnology course I took in Costa Rica, and my own research, so keep checking back for new posts!
For this week, I’m featuring another common, and highly photogenic orbweaver of the Americas: Argiope aurantia. I was out doing field work today, and these spiders were EVERYWHERE! Must be mating time. They are so beautiful, and very large (females can be almost 1.5″ long), so my camera can actually handle taking nice pictures of them. I’m only posting the pictures that I took today, but there are tons of awesome pictures of this species online if you do a little searching. Lots of videos, too.
So, what’s interesting about this species, you ask (besides that it is awe-inspiring… )? First, its current scientific name, Argiope aurantia, describes the colors of the spider, as Argiope means “silver-faced” and aurantia is derived from a word meaning “gold” (See wikipedia for a list of its previous scientific names and this website for a longer history of the name “Argiope aurantia”). In the western U.S., this species is commonly referred to as the Golden Orbweaver or the Golden Silk Orbweaver. However, in the southern U.S., this species is commonly referred to as the Black-and-yellow Argiope, and a different species (Nevila clavipes) is commonly referred to as the Golden Orbweaver, causing some confusion as to what the common name of Argiope aurantia should be. Other common names it has are the Yellow Garden Spider, and the Writing Spider, plus varieties of all of its common names pop up here and there. It’s interesting how the same species can have so many different names, presumably because it spans such a large region of the world.
Their webs are nothing short of spectacular. A couple of the webs I saw today had perfect orbs that were almost two feet in diameter, though others were a little more normal, coming in around 6in-1ft. I saw some females sitting directly in the center of their webs, and others were off sitting on leaves or branches about one foot away, waiting for prey to fly into the web (or hiding from me). Curiously, individuals of this species build their webs with a zig-zag (adults) or circular (juveniles) stabilimentum, that is rather conspicuous (at least to humans). There are various hypotheses as to why they might do this, and supposedly these structures inspired E.B. White in writing Charlotte’s Web (See more on the hypotheses here and here).
Because of their size, capturing large prey isn’t difficult. I saw one capture a very large grasshopper, but I had unfortunately left my camera in the car and couldn’t film it. However, it looked something like this and she did not stop to eat it once she had wrapped it up. Like other orbweavers, she will probably leave it until nighttime, when she takes down her web, and eats it, before building a new one. When I had my camera with me later, I found another web that had a few small insects wrapped up in it (see example below).
This species is NOT a danger to humans, despite how large and brightly-colored individuals are (See this discussion for more info). So, don’t be scared if you see any around in the next few months. Especially since they are so beautiful!
One of the things that I love most about my job is the chance to learn something new and exciting everyday, even when I am on vacation. For instance, while I was home in the SF Bay Area last weekend, my dad decided to show me a number of cool spiders that he has found recently while gardening. One of them was this beautiful, and seemingly common orbweaver, Araneus diadematus. I’m sure that I saw this species a thousand times growing up, but being afraid of spiders, never took the time to really appreciate how interesting and beautiful it really is. Here are a couple pictures I took of a male next to my parents’ house, but if you click on a few of the hyperlinks in this post, you can see some professional photos of them. ARKive has some great videos, as well.
Some facts about Araneus diadematus:
- Commonly known as the “European Garden Spider,” or the “Cross Orbweaver.” The “Cross” name comes from the distinctive pattern on the dorsal side (the “back”) of the abdomen.
- Occurs throughout North America and Europe.
- Sexual cannibalism does occur in this species. In this case, females will sometimes eat males either before or after sex, depending on a variety of physical states (e.g. how hungry she is). (See: Roggenbucketal2011)
- Like many orbweavers, individuals will take down their webs at night, eat the web (along with any insects that are caught in the web), and build a new web in the morning.
- Spiderlings disperse through a behavior called “ballooning,” in which individuals release a bit of silk that catches in the wind, carrying the spider away from its original home. (More info on ballooning in spiders)