“Websites” to check out this fall

Spinybacked Orbweaver with Moustache
Creative Commons License photo credit: mrspiderjoe

Every year about this time, we get lots of calls from people asking about the large, showy spiderwebs they see in their yards and gardens.  Almost always, the web-builder in question is the spinybacked orbweaving spider, Gasteracantha cancriformis

Here’s where that Greek and Latin roots class comes in handy:  the genus name means “stomach spine,” the species name means “crab-shaped.”  At about ½” across when fully grown, it’s a rather small orbweaver, especially compared to the size of its web, which can be well over three feet across.  The “signature” feature of a Gasteracantha web are the white tufts of silk – that from a distance look like white dashes – mostly placed along the outer support (foundation) lines of the web.   These tufts don’t function in prey capture, but may give passing birds or other animals a head’s up that the web is there.  The entire web is a beautiful work of art, especially when it reflects the oblique rays of the early morning or evening sun.

The spider too is quite pretty when you look close.  The flattened abdomen’s upper surface appears coated with shiny enamel paint, and may be red, yellow, white, or black.  Black or sometimes red spines radiate from the abdomen’s edge.  Here’s a picture submitted by Troy of a beautiful red specimen (notice the tufts of silk).

Some people call them “crab spiders,” but true crab spiders do not build webs – they lie in wait for their prey in the center of flowers and are often pastel-colored.  Coolest of all – some can change color over time to match their background, e.g., if they move to a different flower.

ICPspider.JPG
Banana Spider
Creative Commons License photo credit: Lyndi&Jason

Other orbweavers you may notice at this time of year are the garden spider, Argiope aurantia, and the banana spider or golden orbweaver, Nephila clavipesArgiope webs are large and symmetrical, but instead of silk tufts, these spiders weave a thickened cross or zigzag (called a stabilimentum) across the center of the web.  I am sure that Wilbur the Pig’s friend Charlotte was an Argiope – no doubt E.B. White got the idea of writing words in the web from seeing the stabilimentum. 

In contrast, banana spiders build large, messy webs of extremely strong, golden silk.  Often there are several individuals of different sizes in the golden orb webs.  Banana spiders are very common in wooded areas south and west of Houston (e.g., Armand Bayou and Barker Cypress), and we usually have one or more on display in the Insect Wing.

Why do we see orbweaving spiders mostly in the fall?  I suspect that they are around all summer, but both they and their webs are much smaller earlier in the season.  By the way, most web-building spiders you notice are females; male orbweavers are much smaller.  All three species mentioned above overwinter in the egg stage – the adults die at the end of the fall season, leaving only an egg sac behind.

Orbweaving spiders are completely harmless to humans and will not bite.  Indeed, they are highly beneficial because they catch a variety of insects in their large webs.  You can think of them as “green” and silent bug-zappers! 

So – next time you see a big spider web, take a moment to look for the hardworking and talented spider that built it, and tell it (her) “hello, and thanks!”

Summer Encounters – Brazos Bend State Park

Oak tree

Welcoming Oak Tree

Last summer I was introduced to Brazos Bend State Park. I found many amazing animals living amongst the tall swamp reeds and old oak trees. Recently, I spent a weekend down there camping with my family. I’d like to share some of the beautiful animals we encountered on this visit.

Now, like many people, I’m not particularly fond of certain small, creepy-crawlies, including my least favorite: ticks! Unfortunately (and much to my dismay) I was feasted upon by one tiny tick. However, when I was given an opportunity to watch a spider feast upon its own meal, I didn’t feel the same distress. Near our campsite, there were plenty of enormous spiders for us to observe. I was astounded by the size and beauty of the Golden Silk Spider, Nephila clavipes, often called the Banana Spider.

Golden Silk Spider

Golden Silk Spider

She is relatively harmless to humans, but has an impressive web and can take down dragonflies. This species are also a cannibalistic species, preying upon their own kind. The males live on the backside of the web from the female, risking their lives to mate when the time is right. I witnessed a large female dining on a smaller female early one morning. Apparently, it is not such a good idea to build your web directly in front of a larger, hungrier silk spider! If you look closely at the photo to the right, you may be able to see the much smaller male sitting a couple of inches to the left of the female.

As a side note, I learned that another spider, the Brazilian Wandering Spider, Phoneutria nigriventer, is also often called a Banana Spider. This spider can be fatal to humans and should not be taken lightly.

Another favorite invertebrate that I was able to find at Brazos Bend State Park is the firefly (not to be confused with the excellent, but short TV series Firefly), also known as lightning bugs. Last summer was the first time I had ever seen them and I was still very excited when I saw them again this summer. I also managed to catch one and study it up close, watching as the abdomen slowly glowed on and off. These beetles use their bioluminescence to communicate with each other. Each species of firefly has their own, distinct pattern they flash to attract a mate. The male flashes his pattern while flying around, hoping to find a female responding to his light with her own light show. However, some females will mimic the pattern of another species in order to catch their dinner!

Lightning Bug

Lightning Bug

While walking around Elm lake, you can’t help but notice all of the beautiful water birds. They share the lake with the alligators, seemingly unaware of the dark eyes resting at the edge of the water’s surface. During the summer, you can easily spot pairs of white ibises, egrets & herons, common moorhens, black-bellied whistling ducks, and on occasion you may spot an osprey or wood stork. Below, I’ve posted a photo of a Green Heron, Butorides virescens, looking for his lunch amongst all of the duckweed. Green Herons typically hunt small aquatic animals including invertebrates, small fish, & frogs. It has been known to “bait” for fish, dropping a small item on the surface of the water and waiting to catch the fish attracted to the lure.

Green Heron

Green Heron

The last animal I want to bring up from my encounters at Brazos Bend State Park is the Nine-Banded Armadillo, Dasypus novemcinctus. We were hiking on a path near the George Observatory while we waited to buy tickets to look through the telescopes later that evening. My well-trained ears told me there was an animal moving about in the underbrush nearby. I turned to look and couldn’t believe my eyes when I saw my first armadillo! The novelty of this new mammal had me snapping pictures left and right, spending a good 20 minutes observing its search for food.

Nine Banded Armadillo

Nine-Banded Armadillo

Eventually, my dogs noticed this new creature and started barking. By this time, the armadillo had meandered right near the path and upon being frightened by the dogs, he did an about-face and nearly ran straight into my friend’s legs! He eventually found his way back to the denser foliage and continued foraging for lunch. After this first encounter, we later came across 4 more juveniles, these were much quicker to run away from us than the first adult we observed.

The nine-banded armadillo may be opportunistic, eating whatever food they come across, but mostly they eat a wide variety of invertebrates: caterpillars, scarab beetles, grubs, termites, & worms. They will also eat carrion and occasionally crustaceans, fruit, reptiles & amphibians. Armadillos are excellent diggers but have poor vision. When frightened, they may jump straight into the air!

Armadillos are capable of crossing water in two interesting ways. In order to get around the problem of their heavy armor, the armadillo can hold its breath and simply walk across the bottom of a body of water. However, they are able to swim by inflating their stomach to offer some bouyancy. Nine-banded armadillos have identical quadruplets around March, the young staying with the mother for several months.

If you would like to see more photos from Brazos Bend State Park, please visit the BBSP Flickr group webpage. You can also find a wide variety of photos from HMNS at their Flickr group page as well. I am still working on updating my own Flickr page with Museum-related photos, but in the meantime, enjoy this one last photo of the largest alligator I’ve seen at Brazos Bend. I was standing directly above him on a dock at Hale lake. My best guess at his length: 12-14 feet long!

Large Alligator

American Alligator