Trinity River Audubon Center - June 14, 2013

June 14, 2013

Back at the Trinity River Audubon Center off of I-45 and Loop 12 just a few minutes south of downtown Dallas.

Trinity River Audubon Center

6500 Great Trinity Forest Way (formerly 6500 S. Loop 12)

Dallas, TX 75217

Phone: 214-398-TRAC (8722)

 

The location I found today is not actually on the trail map.  It is on a mowed trail that begins at the parking lot.

 

 

 

This is an excellent location with many tall plants (still green because of the rain we are having this month).  the trail runs approximately north and south which puts one side of the trail in sun and the other in shade.

 

I found many young Argiope spiders on webs with stabilimenta.  These are all female, about 6, and I hope to watch them through out the summer to see when they make egg sacs.  Because they are located so closely together it seems reasonable that they are probably sisters from the same egg sac.

 

Eastfield College has a gene sequencer and it would be an excellent project to sequence some genes  and see if this is true.

 



Argiope positioned on her stabilimenta.

A closer view of the spider.

 

Another Argiope female, but with a different stabilimenta pattern.  One theory is that by positioning herself on the stabilimenta, the spider becomes less visible to predators such as birds. 



I know that the male Argiope are much smaller than the females.  I found several of these smaller webs with stabilimenta that I thought might belong to males, but have yet to find one.

 

At one point I saw a very small spider moving quickly across this web - very quickly.  As I watched the spider moved to the top of the web and then ballooned away. 

 

Ballooning is a process that spiderlings use to disperse.  They climb to a high branch or spot and begin to release a silk thread which is picked up by the wind.  When they get enough silk out it lifts them into the air where they will float to a new location.

 

I hadn't noticed the ballooning silk so I suspect the little spider was being pulled across the web as much as crawling. 

 

 

 I found several of these crab spiders on vegetation.  The sit with their two front legs extended waiting to grab what every comes by.

 Here is another cobweb spider which has formed a web between two leaves. 

I found lots of snout beetles on many of the taller plants.  These guys were ridiculously easy to capture because of a defensive behavior.  When disturbed they simply let go of the leaf and fall.  All I had to do was open the collecting jar, put it under the leaf, and poke the beetle causing it to fall into the jar.

 These little guys are amazingly tough as I found out when I tried to pin them.  I couldn't even get their legs to move laterally. 

 

Leica S8AP0 Dissecting Scope

 

 Image of collected beetle.  . Notice the backward facing antennae.

 Close up of eye.  There are slits in the proboscis for the antennae to fold into.

Some heavy duty tarsal claws.

 

Hatachi S-3400N Scanning Electron Microscope

 

 Hello there.  Front-on view of eyes.  [93x]



Head and thorax.  You can clearly see the slit for the antenna and the large tarsal claws.  [20x]

The eyes have what appears to be eyelashes even though this animal does not blink its eyes.  Notice the Y-shaped hairs to the right.  [110x]

 

 

 I will admit that I am pretty excited about this.  It appears that the ommatidia are surrounded by what looks like bacteria.  Definitely needs further investigation.  If I can collect more of these snout weevils and confirm many or all of them have the "bacteria" around their ommatidia, I will attempt to culture them.  (Sadly, when I went out on the next week I couldn't find any snout weevils in the same location though the damage to the leaves in the area showed they had been there.)   [800x]

 Ommatidia with surrounding rod shaped structures.  [1,900x]

More of the bacteria-like structures in the hairs above the eye.  Could be some plant material or residue.  [400x]

 

Homopterans, or hoppers, are true bugs - actually the only insect that can be called a bug. On most stems there are hoppers who also have a pretty interesting behavior.  They hide behind the stem of the plants to avoid predators.  If you reach out for one of these bugs they will quickly scoot sideways behind the stem.  Reach behind the stem and the scoot back into view.  You can chase them around for a while until they finally fly away.


Note:  David H. Kattes in  his book Insects of Texas states that order Homoptera has been absorbed into order Hymenoptera.

Kattes, David H. Insects of Texas. College Station: Texas A&M UP, 2009. Print.

 Close up of the bottom hopper from the image above.

 Close up of the top hopper in the previous image.

Leica S8AP0 Dissecting Scope

 Back in the lab.

 Collected insect in the lab.

 

 

 

This is the flower of the Illinois Bundle Flower - Desmanthus illinoesis.  The fruit of this wildflower can be seen in the June 4 blog.

 

From Wildflowers of Texas - "These clusters are much sought for use in dried arrangements.  High in protein, this plant is considered one of our most important native legumes, for livestock and wildlife.  Readily eaten by them, it is an excellent range-condition indicator."

 

Ajilvsgi, Geyata. Wildflowers of Texas. Fredericksburg: Shearer Publishing, 1984. Print. Illinois Bundleflower - Desmanthus illinoensis P. 57 

 

I welcome your comments on this blog - really - I mean it.

 

 

All images are licensed under Creative Commons Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)

 

Feel free to use, copy, or edit as you see fit, but be sure to give attribution to Eastfield College, Mesquite, TX.  Images may not be sold.

 

 

 

 

 

Trinity River Audubon Center - June 4, 2013

Eastfield College will offer a student research class beginning in Fall 2013.  (BIOL 2389 for those interested in enrolling.)  The focus of this class will be entomology and Eastfield is partnering with the Trinity River Audubon Center (TRAC) as the main location for our field work. 

If you have never been to TRAC it is well worth the visit.  It is a beautiful location with lots of well maintained trails and tons of wildlife located just a few minutes south of downtown Dallas.

Trinity River Audubon Center

6500 Great Trinity Forest Way (formerly 6500 S. Loop 12)

Dallas, TX 75217

Phone: 214-398-TRAC (8722)

http://trinityriver.audubon.org/

In preparation for the class I will be going into the field once a week all summer.  This is an electronic journal of what I find at Trinity River Audubon Center on my visits.
 
June 4, 2013

I worked at two locations.  Location 1 is located northeast of the parking area.  Location 2 is south of the visitor center.

 

 

Location 1:



June was unusually mild and wet for this area resulting in tall and vigorously growing grasses and wildflowers.  The trail is surrounded by Coreopsis tinctoria.



Whistling Duck Pond - Looking east



Coreopsis tinctoria



 Coreopsis tinctoria
 

 A close-up view.  I had not planned to study wildflowers, but the trail on this particular day was truly spectacular.

 

This is a spider Argiope - a yellow garden spider.  The zig zag pattern in its web is called stabilamenta.  There are lots of theories about its function.

 

 

Farther off the trail to the east I came across a series of small cob webs and their spiders.  There were several of these nests on the tops of each dead plant.  My hand is in the picture to give scale and to help with focusing the camera.

 

Questions:

1)  What is their density - per bush, per area?

2)  What would happen if you moved a spider to a new plant tip that was occupied?

3)  How do they find these taller plants?

 

Cobwebs at the tops of dead plants like the one shown above.

Location #2

After spending some time in the open grassy areas I decided to move into the trees to look for more spiders.


 

The trail toward the river

 

A wound in a tree is producing sap that attracts some butterflies.



 A closer look.

In the trees I came across some occupied spider webs.  What caught my attention was the combination of a cob web and an orb web.  The spider is in a conical retreat in the middle of the cob web.  After doing some reading I came across the fact that certain cob web spiders will build their webs on top of an orb web, preying on the orb spider and any prey it has caught.

 

 

 

The images above and below show the spider in its retreat.  I decided to not collect any of these spiders at this time.

 

 

In the image above you can also see some of the wrapped prey items the spider has caught. 

 

The other spider I found at this location was an orb web spider.  I use a point and shoot camera that wouldn't focus on the web, so I indicated its location in the photo.  Also notice the arrow showing the owner of the web in his retreat.

 

As you can see, this spider has connected a small dead leaf to the underside of a live leaf and sits upon it to hide himself.  This was the only one of this type of spider I saw today so I did not collect it. 

Questions:

1)  How does this spider do this?  - How does it select the leaf and haul it into place. 
2)  If I remove the spider from its web and retreat, can I induce it to build another retreat?



The shady area along this trail held another surprise - poison ivy.  I took these images to show my students what it looks like.

 Leaves of three, leave it be!  Notice the red on the stem where the leaves are attached.

I was on site for about 3 hours on this first day of observation.  Once I picked a spot I didn't even have to move to see lots of great organisms. 

All images carry a Creative Commons Attribution-Non Commercial License.
http://creativecommons.org/licenses/by-nc/3.0/






I welcome all comments on this posting.